The Difference Between Activity When in Bed and Out of Bed. II. Subjects on 27-Hour “Days”

Nine healthy subjects have been studied while exposed to the normal alternation of light and dark, but with their sleep and activity pattern adjusted to a 27-h “day” for 17 imposed “days.” Rectal temperature showed clearly the competing influences of 27-h and 24-h components, and these were separated by the method of “purification.” The method indicated that the endogenous component had a constant amplitude throughout the experiment and remained entrained to solar (24-h) time; by contrast, the exogenous component followed the imposed 27-h “day” and increased rectal temperature in proportion to the amount of subjects' activity. Wrist movement was used to assess activity while in bed (attempting sleep) and out of bed (when naps were forbidden). While these results confirmed adherence of the subjects to the imposed 27-h “days,” they also showed that the dichotomy between “out of bed” activity and “in bed” inactivity depended on the phase relationship between endogenous (24h) and exogenous (27h) components. Thus, the dichotomy was highest and was equal to that during control days (with a conventional 24-h life-style) when the two components were in phase and lowest when the solar and imposed day were in antiphase. This was due to changes in activity, both during time spent in bed and out of bed.

We confirm that this protocol can produce valuable information about the properties of the circadian system in humans and the value of the process of purification of temperature data. We have established also that the very simple and noninvasive measurement of wrist movement, coupled with its use to calculate dichotomy indices, provides valuable information that both confirms and extends the results obtained from the more conventional (butalso more invasive) measurement of rectal temperature.     

Diel behavior in moths and butterflies: a synthesis of data illuminates the evolution of temporal activity

Lepidoptera (butterflies and moths) are one of the most taxonomically diverse insect orders with nearly 160,000 described species. They have been studied extensively for centuries and are found on nearly all continents and in many environments. It is often assumed that adult butterflies are strictly diurnal and adult moths are strictly nocturnal, but there are many exceptions. Despite the broad interest in butterflies and moths, a comprehensive review of diel (day-night) activity has not been conducted. Here, we synthesize existing data on diel activity in Lepidoptera, trace its evolutionary history on a phylogeny, and show where gaps lie in our knowledge. Diurnality was likely the ancestral condition in Lepidoptera, the ancestral heteroneuran was likely nocturnal, and more than 40 transitions to diurnality subsequently occurred. Using species diversity estimates across the order, we predict that roughly 75-85% of Lepidoptera are nocturnal. We also define the three frequently used terms for activity in animals (diurnal, nocturnal, crepuscular), and show that literature on the activity of micro-moths is significantly lacking. Ecological factors leading to nocturnality/diurnality is a compelling area of research and should be the focus of future studies.     

Tracking the rise of eukaryotes to ecological dominance with zinc isotopes

The biogeochemical cycling of zinc (Zn) is intimately coupled with organic carbon in the ocean. Based on an extensive new sedimentary Zn isotope record across Earth's history, we provide evidence for a fundamental shift in the marine Zn cycle ~800 million years ago. We discuss a wide range of potential drivers for this transition and propose that, within available constraints, a restructuring of marine ecosystems is the most parsimonious explanation for this shift. Using a global isotope mass balance approach, we show that a change in the organic Zn/C ratio is required to account for observed Zn isotope trends through time. Given the higher affinity of eukaryotes for Zn relative to prokaryotes, we suggest that a shift toward a more eukaryote‐rich ecosystem could have provided a means of more efficiently sequestering organic‐derived Zn. Despite the much earlier appearance of eukaryotes in the microfossil record (~1700 to 1600 million years ago), our data suggest a delayed rise to ecological prominence during the Neoproterozoic, consistent with the currently accepted organic biomarker records.     

Blood-brain barrier-associated pericytes internalize and clear aggregated amyloid-β42 by LRP1-dependent apolipoprotein E isoform-specific mechanism

Background

Clearance at the blood-brain barrier (BBB) plays an important role in removal of Alzheimer’s amyloid-β (Aβ) toxin from brain both in humans and animal models. Apolipoprotein E (apoE), the major genetic risk factor for AD, disrupts Aβ clearance at the BBB. The cellular and molecular mechanisms, however, still remain unclear, particularly whether the BBB-associated brain capillary pericytes can contribute to removal of aggregated Aβ from brain capillaries, and whether removal of Aβ aggregates by pericytes requires apoE, and if so, is Aβ clearance on pericytes apoE isoform-specific.

Methods

We performed immunostaining for Aβ and pericyte biomarkers on brain capillaries (<?6 μm in diameter) on tissue sections derived from AD patients and age-matched controls, and APP^Swe/0 mice and littermate controls. Human Cy3-Aβ42 uptake by pericytes was studied on freshly isolated brain slices from control mice, pericyte LRP1-deficient mice (Lrp^lox/lox;Cspg4-Cre) and littermate controls. Clearance of aggregated Aβ42 by mouse pericytes was studied on multi-spot glass slides under different experimental conditions including pharmacologic and/or genetic inhibition of the low density lipoprotein receptor related protein 1 (LRP1), an apoE receptor, and/or silencing mouse endogenous Apoe in the presence and absence of human astrocyte-derived lipidated apoE3 or apoE4. Student’s t-test and one-way ANOVA followed by Bonferroni's post-hoc test were used for statistical analysis.

Results

First, we found that 35% and 60% of brain capillary pericytes accumulate Aβ in AD patients and 8.5-month-old APP^Sw/0 mice, respectively, compared to negligible uptake in controls. Cy3-Aβ42 species were abundantly taken up by pericytes on cultured mouse brain slices via LRP1, as shown by both pharmacologic and genetic inhibition of LRP1 in pericytes. Mouse pericytes vigorously cleared aggregated Cy3-Aβ42 from multi-spot glass slides via LRP1, which was inhibited by pharmacologic and/or genetic knockdown of mouse endogenous apoE. Human astrocyte-derived lipidated apoE3, but not apoE4, normalized Aβ42 clearance by mouse pericytes with silenced mouse apoE.

Conclusions

Our data suggest that BBB-associated pericytes clear Aβ aggregates via an LRP1/apoE isoform-specific mechanism. These data support the role of LRP1/apoE interactions on pericytes as a potential therapeutic target for controlling Aβ clearance in AD.

     

Thylakoid polypeptide composition and light-independent phosphorylation of the chlorophyll a,b-protein in Prochloron, a prokaryote exhibiting oxygenic photosynthesis

Thylakoids of the prokaryote Prochloron, present as a symbiont in ascidians isolated from the Red Sea at Eilat (Israel), showed polypeptide electrophoretic patterns comparable to those of thylakoids from eukaryotic oxygen-evolving organisms. Low temperature, fluorescence spectroscopy of Prochloron, having a chlorophyll a/b ratio of 3.8–5, and frozen in situ, demonstrated the presence of Photosystem II chlorophyll-protein complex emitting at 686 and 696 nm, as well as the emission band of Photosystem I at 720 nm which was so far not observed in Prochloron species. The latter emission was absent, if the cells or thylakoids were isolated prior to freezing. Energy transfer from chlorophyll b to chlorophyll a could be demonstrated to occur in vivo. The chlorophyll a,b-protein complex of Photosystem II, isolated by non-denaturing polyacrylamide gel electrophoresis, contained one major polypeptide of 34 kDa. The polypeptide was phosphorylated in vitro by a membrane-bound protein kinase which was not stimulated by light. A light-independent protein kinase activity was also found in isolated thylakoids of another prokaryote, the cyanophyte Fremyella diplosiphon. State I–State II transition could not be demonstrated in Prochloron by measurements of modulated fluorescence intensity in situ. We suggest that the presence of a light-independent thylakoid protein kinase of Prochloron, collected in the Red Sea at not less than 30 m depth, might be the result of an evolutionary process whereby this organism has adapted to an environment in which light, absorbed preferentially by Photosystem II, prevails.     

Seasonal reproductive cycle of the Galápagos tortoise (Geochelone nigra) in captivity

The reproductive physiology of nine Galápagos tortoises (Geochelone nigra) was studied from February 1988 to May 1989. The study encompassed the annual reproductive cycle to include complete mating and nesting sequences. Male (n = 4) and female (n = 5) seasonal reproductive changes were determined throughout the study with endocrine analysis and ultrasonographic examinations. Males displayed a prenuptial rise in serum testosterone (x― ±SE = 6.62 ± 0.92 ng/ml in August) during which gonadal maturation and spermatogenesis are thought to occur. The male reproductive cycle appears consistent with the prenuptial spermatogenic pattern exhibited by other tropical turtles. In the females, testosterone rose during the mating period (x― ± SE = 499.3 ± 124.6 pg/ml in October) prior to ovulation and is probably related to receptivity in the females. Progesterone was more variable, but also peaked during the mating period (x― ± SE = 1,017.2 ± 220.6 pg/ml in October) and appears related to ovulation. Estradiol rose several months prior to mating (x― ± SE = 75.5 ± 11.9 pg/ml in July) and was correlated with increased serum calcium levels. This increase in estradiol is thought to stimulate vitellogenesis several months prior to mating. Nesting occurred from November 1988 to April 1989, during which six clutches were laid. Clutch size ranged from eight to 17 eggs. Both male and female Galápagos tortoises display seasonal physiological changes that function to regulate annual reproductive patterns. Zoo Biol 17:505–517, 1998. © 1998 Wiley-Liss, Inc.     

Identifying the plant‐associated microbiome across aquatic and terrestrial environments: the effects of amplification method on taxa discovery

Plants in terrestrial and aquatic environments contain a diverse microbiome. Yet, the chloroplast and mitochondria organelles of the plant eukaryotic cell originate from free‐living cyanobacteria and Rickettsiales. This represents a challenge for sequencing the plant microbiome with universal primers, as ~99% of 16S rRNA sequences may consist of chloroplast and mitochondrial sequences. Peptide nucleic acid clamps offer a potential solution by blocking amplification of host‐associated sequences. We assessed the efficacy of chloroplast and mitochondria‐blocking clamps against a range of microbial taxa from soil, freshwater and marine environments. While we found that the mitochondrial blocking clamps appear to be a robust method for assessing animal‐associated microbiota, Proteobacterial 16S rRNA binds to the chloroplast‐blocking clamp, resulting in a strong sequencing bias against this group. We attribute this bias to a conserved 14‐bp sequence in the Proteobacteria that matches the 17‐bp chloroplast‐blocking clamp sequence. By scanning the Greengenes database, we provide a reference list of nearly 1500 taxa that contain this 14‐bp sequence, including 48 families such as the Rhodobacteraceae, Phyllobacteriaceae, Rhizobiaceae, Kiloniellaceae and Caulobacteraceae. To determine where these taxa are found in nature, we mapped this taxa reference list against the Earth Microbiome Project database. These taxa are abundant in a variety of environments, particularly aquatic and semiaquatic freshwater and marine habitats. To facilitate informed decisions on effective use of organelle‐blocking clamps, we provide a searchable database of microbial taxa in the Greengenes and Silva databases matching various n‐mer oligonucleotides of each PNA sequence.     

Substituted N-(3,5-dichlorobenzenesulfonyl)-L-prolyl-phenylalanine analogues as potent VLA-4 antagonists

A series of substituted N-(3,5-dichlorobenzenesulfonyl)-L-prolyl- and alpha-methyl-L-prolyl-phenylalanine derivatives was prepared as VLA-4/VCAM antagonists. The compounds showed excellent potency with a wide variety of neutral, polar, electron withdrawing or donating groups on the phenylalanine ring (IC50 approximately 1 nM). Heteroaryl ring substitution for phenylalanine was also well tolerated. Pharmacokinetic studies in rat were performed on a representative set of compounds in both series.     

Studies of Delta-Aminolevulinic Acid Dehydrase from Skeletonema costatum, a Marine Plankton Diatom

The accumulation of δ-aminolevulinic acid and activities of δ-aminolevulinic acid dehydrase were examined in the marine diatom, Skeletonema costatum, grown in the presence of levulinic acid. Levulinic acid concentrations greater than 10 mm affect growth and morphology, and inhibit chlorophyll synthesis. The algae recover from the effects of levulinic acid after 48 hours of exposure. The recovery is characterized by increased cellular cholorphyll content, decreased δ-aminolevulinic acid accumulation, decreased 3-(3,4-dichlorophenyl)-1, 1-dimethylurea-enhanced in vivo fluorescence, and the induction of a levulinic acid-activated δ-aminolevulinic acid dehydrase which does not follow Michaelis-Menten kinetics. The data indicate that levulinic acid blocks may be ineffective in vivo, and that δ-aminolevulinic acid is metabolized to amino and dicarboxylic acids. δ-Aminolevulinic acid dehydrase activities are used to estimate the capacity for chlorophyll synthesis. Results suggest this diatom may be capable of rapid chlorophyll turnover, which would allow the plant to light-shade adapt on the time scales appropriate to vertical mixing rates in the sea.     

Water-soluble natural products from seaweed have limited potential in controlling bacterial pathogens in fish aquaculture

Seaweeds producing natural products with in vitro efficacy against bacterial pathogens offer the opportunity for therapeutic services in fish aquaculture, for example inhibiting the growth of pathogens through the direct release of bioactive metabolites into the culture environment. The red alga Asparagopsis taxiformis was used to test this hypothesis because of its effective natural products and mechanisms to release these metabolites into the surrounding environment and because it can be cultivated intensively in land-based systems. Here we quantify the release, accumulation and residence time of the major halogenated metabolites from A. taxiformis in the cultivation medium and subsequently test the in vitro bioactivity of these water-soluble metabolites against multiple strains of the pathogenic bacterium Streptococcus iniae. The two major halogenated metabolites in A. taxiformis (bromoform and dibromoacetic acid) were released into the water and reaching steady-state concentrations of 27.7?±?1.5 μg L^?1 and 4.8?±?1.3 μg L^?1, respectively, under standard cultivation conditions. This water delayed the in vitro growth of the pathogenic bacteria S. iniae but did not prevent it. Increasing the levels of A. taxiformis metabolites in the water by three orders of magnitude with aqueous extracts of biomass inhibited the growth of S. iniae, but it was also toxic to fish. In an immersion challenge experiment, intermediate non-ichthyotoxic levels of A. taxiformis metabolites were ineffective as a treatment for barramundi infected by S. iniae. The evidence suggests that there is little potential for A. taxiformis bioactive metabolites to provide therapy services to fish infected with S. iniae.