Mate guarding in relation to seasonal changes in the energy reserves of two freshwater amphipods (Gammarus fossarum and G. pulex)

1. We assessed sex‐specific seasonal changes in major energy storage compounds (triglycerides, glycogen) in Gammarus fossarum and Gammarus pulex collected from the field, with respect to their reproductive activity. 2. The dynamics of stored energy followed a seasonal pattern in both species and sexes. Moreover, over a 4‐year period, these changes were independent of the year in which they were investigated. Stored energy reached a peak in late winter, but was depleted in late summer and early autumn, coinciding with the reproductive periods. 3. Triglyceride (annual mean ± SD) accounted for 79.7 ± 11.9% of the total stored energy and was responsible for the seasonal pattern. In contrast, glycogen contributed a lesser percentage (20.3 ± 11.9%). Over the study period, the amount of stored energy ranged between 0.39 and 4.08 kJ g^?1 dry mass (triglyceride: 0.19–3.69 kJ g^?1 dry mass; glycogen: 0.14–0.80 kJ g^?1 dry mass). 4. In both species, the energy reserves of males were drastically depleted shortly before the cessation of precopulatory mate guarding in the field, thus offering a bioenergetic explanation for the reproductive period in these two widespread species.     

Cytoplasmic free calcium concentration in porcine platelets: Regulation by an intracellular nonmitochondrial calcium pump and increase after thrombin stimulation

Mechanisms are assumed to exist in the resting platelet which maintain the concentration of cytoplasmic free calcium below that level required to activate cellular responses. To assess such processes the porcine platelet plasma membrane was selectively lysed with digitonin and the uptake (or flux) of free calcium monitored by an extracellular calcium electrode. Lysis resulted in an immediate lowering of the extracellular free calcium, due to the action of intracellular organelle(s) acting on the extracellular space through the permeabilized plasma membrane. In resting platelets, the rate of calcium uptake was first order with respect to the extracellular prelytic calcium concentration, and hence the cytoplasmic free concentration was found to be 1·10^?7 M by extrapolation to a point of zero flux (i.e., the null point). This approach could not be used with thrombin-stimulated platelets, as external calcium was required for both secretion of ATP + ADP and aggregation. Nevertheless, evidence for an increase in cytoplasmic free calcium after thromin stimulation was obtained. Metabolic inhibitors and agents known to inhibit calcium uptake by mitochondria had no effect on the calcium flux following lysis, indicating different mechanisms for calcium homeostasis in the platelet when compared with other cell types (e.g., liver). Levels of ionophore A23187, which caused platelet aggregation, gave a massive release of the nonmitochondrial pool of calcium into the cytoplasmic space. Thus, in porcine platelets an intracellular energy-requiring calcium pump, which sequesters calcium in a nonmitochondrial membranous compartment, is crucial for intracellular calcium homeostasis.     

Effects of central administration of arginine vasotocin on monoaminergic neurotransmitters and energy metabolism of rainbow trout brain

In a first set of experiments, intracerebroventricular (ICV) treatment of 1 μl 100 g⁻¹ body mass of Cortland saline containing different doses (1–20 nmol μl⁻¹) of arginine vasotocin (AVT) produced after 180 min dose‐dependent changes in levels of brain neurotransmitters in several brain regions and pituitary of rainbow trout Oncorhynchus mykiss . Thus, an enhancement of serotonergic and dopaminergic activity, together with a decreased noradrenergic activity, were observed both in the hypothalamus and pituitary of AVT‐treated fish. In the other brain regions assessed, only increased serotonergic activity in the optic lobes, and decreased dopaminergic activity in the telencephalon of AVT‐treated fish were noticed. Changes observed in monoamine levels resemble those observed during osmotic adaptation of euryhaline fishes. In a second set of experiments, fish were ICV injected with AVT as described above to assess changes in several variables of brain energy metabolism. The results obtained show a dose‐dependent enhancement of brain glycogenolytic potential in the brain of AVT‐treated fish, that again resemble the changes observed in euryhaline fishes during osmotic acclimation.     

Photoperiodic effect on some enzymes and metabolites in diapausingAntheraea mylitta pupae andPhilosamia ricini larvae during development

The variation in acid phosphatase (EC 3.1.3.2) activity inAntheraea mylitta was similar in all light and dark groups exposed to different photophases (LD =0:24, 24:0, 18:6, 14:10, 10:14 and 12:12 h) maintaining all along a higher activity than its alkaline counterpart. The highest activity was recorded on day 82 in LD group 10:14 h. The non-diapausingPhilosamia ricini larvae registered highest activity in LD group 0:24 h on day 5. Alkaline phosphatase (EC 3.1.3.1) activity was low all through metamorphosis in both the lepidopterans, although significantly elevated activity was observed on day 5 in larvae of allPhilosamia ricini LD regimens and on day 82 inAntherae mylitta. Photoperiodic effect on Phosphorylase (EC 2.3.1.1) activity, glycogen and inorganic phosphates content have also been studied. Exposure to LD 10:14, 14:10 and 18:6 h provoked early diapause termination inAntheraea mylitta. The non-diapausingPhilosamia ricini was unaffected in moth emergence but the emerged adults of LD 24:0 and 0:24 h groups were unhealthy, small and did not mate or oviposit.     

Metabolic responses to acute handling by fingerling inland and anadromous striped bass

Fed and 3-day fasted inland (average mass: 6.97 g) and anadromous (average mass: 6.54 g) striped bass Morone saxatilis fingerlings were held in dipnets above water for 5 min in groups of six. Severity of the response to this handling was measured by whole-body glucose, glycogen, and lactic acid in non-handled bass (considered control level), and then at 30 min, 1, 6, 12, 24 and 48 h recovery. At resting levels, both fed and fasted inland bass showed significantly higher concentrations of the whole body variables than anadromous bass. All four groups of bass showed an increase in lactic acid and glucose immediately after handling, with a concomitant decrease in glycogen. Peak levels of glucose and lactic acid were similar in the four groups. Fasting did not have an effect on the glucose and lactic acid responses, but did affect the glycogen response. The two fasted groups did not return to control glycogen concentrations during the 48-h recovery period. By 48 h, both glucose and lactic acid had returned to control levels. It is concluded that inland and anadromous strains of fingerling striped bass do not differ in their sensitivity to an acute handling stress. Recovery of glycogen energy stores following handling is much better if fish are not fasted before handling.     

Two-hit wonders: The expanding universe of multitargeting epigenetic agents

Multitargeting involves the application of molecules that are deliberately intended to bind to two or more unrelated cellular targets with high affinity. In epigenetic chemical biology and drug discovery, the rational design of multitargeting agents has evolved to a sophisticated level, and there are now five examples that have reached clinical trials. This review covers recent developments in the field and future prospects.     

Metabolic Enzyme Alterations and Astrocyte Dysfunction in a Murine Model of Alexander Disease With Severe Reactive Gliosis

Alexander disease (AxD) is a rare and fatal neurodegenerative disorder caused by mutations in the gene encoding glial fibrillary acidic protein (GFAP). In this report, a mouse model of AxD (GFAP^Tg;Gfap^+/R236H) was analyzed that contains a heterozygous R236H point mutation in murine Gfap as well as a transgene with a GFAP promoter to overexpress human GFAP. Using label-free quantitative proteomic comparisons of brain tissue from GFAP^Tg;Gfap^+/R236H versus wild-type mice confirmed upregulation of the glutathione metabolism pathway and indicated proteins were elevated in the peroxisome proliferator-activated receptor (PPAR) signaling pathway, which had not been reported previously in AxD. Relative protein-level differences were confirmed by a targeted proteomics assay, including proteins related to astrocytes and oligodendrocytes. Of particular interest was the decreased level of the oligodendrocyte protein, 2-hydroxyacylsphingosine 1-beta-galactosyltransferase (Ugt8), since Ugt8-deficient mice exhibit a phenotype similar to GFAP^Tg;Gfap^+/R236H mice (e.g., tremors, ataxia, hind-limb paralysis). In addition, decreased levels of myelin-associated proteins were found in the GFAP^Tg;Gfap^+/R236H mice, consistent with the role of Ugt8 in myelin synthesis. Fabp7 upregulation in GFAP^Tg;Gfap^+/R236H mice was also selected for further investigation due to its uncharacterized association to AxD, critical function in astrocyte proliferation, and functional ability to inhibit the anti-inflammatory PPAR signaling pathway in models of amyotrophic lateral sclerosis (ALS). Within Gfap⁺ astrocytes, Fabp7 was markedly increased in the hippocampus, a brain region subjected to extensive pathology and chronic reactive gliosis in GFAP^Tg;Gfap^+/R236H mice. Last, to determine whether the findings in GFAP^Tg;Gfap^+/R236H mice are present in the human condition, AxD patient and control samples were analyzed by Western blot, which indicated that Type I AxD patients have a significant fourfold upregulation of FABP7. However, immunohistochemistry analysis showed that UGT8 accumulates in AxD patient subpial brain regions where abundant amounts of Rosenthal fibers are located, which was not observed in the GFAP^Tg;Gfap^+/R236H mice.     

Intracellular accumulation of trehalose and glycogen in an extreme oligotroph,Rhodococcus erythropolis N9T-4

An extreme oligotroph, Rhodococcus erythropolis N9T-4, showed intracellular accumulation of trehalose and glycogen under oligotrophic conditions. No trehalose accumulation was observed in cells grown on the rich medium. Deletion of the polyphosphate kinase genes enhanced the trehalose accumulation and decreases the intracellular glycogen contents, suggesting an oligotrophic relationship between among the metabolic pathways of trehalose, glycogen, and inorganic polyphosphate biosyntheses.     

Kinase GSK3β functions as a suppressor in colorectal carcinoma through the FTO-mediated MZF1/c-Myc axis

Colorectal carcinoma (CRC) poses heavy burden to human health and has an increasing incidence. Currently, the existing biomarkers for CRC bring about restrained clinical benefits. GSK3β is reported to be a novel therapeutic target for this disease but with undefined molecular mechanisms. Thus, we aimed to investigate the regulatory effect of GSK3β on CRC progression via FTO/MZF1/c-Myc axis. Firstly, the expression patterns of GSK3β, FTO, MZF1 and c-Myc were determined after sample collection. Lowly expressed GSK3β but highly expressed FTO, MZF1 and c-Myc were found in CRC. After transfection of different overexpressed and interference plasmids, the underlying mechanisms concerning GSK3β in CRC cell functions were analysed. Additionally, the effect of GSK3β on FTO protein stability was assessed followed by detection of MZF1 m6A modification and MZF1-FTO interaction. Mechanistically, GSK3β mediated ubiquitination of demethylase FTO to reduce FTO expression. Besides, GSK3β inhibited MZF1 expression by mediating FTO-regulated m6A modification of MZF1 and then decreased the proto-oncogene c-Myc expression, thus hampering CRC cell proliferation. We also carried out in vivo experiment to verify the regulatory effect of GSK3β on CRC via FTO-mediated MZF1/c-Myc axis. It was found that GSK3β inhibited CRC growth in vivo which was reversed by overexpressing c-Myc. Taken together, our findings indicate that GSK3β suppresses the progression of CRC through FTO-regulated MZF1/c-Myc axis, shedding light onto a new possible pathway by which GSK3β regulates CRC.