Delayed herbivory by migratory geese increases summer‐long CO2 uptake in coastal western Alaska

The advancement of spring and the differential ability of organisms to respond to changes in plant phenology may lead to “phenological mismatches” as a result of climate change. One potential for considerable mismatch is between migratory birds and food availability in northern breeding ranges, and these mismatches may have consequences for ecosystem function. We conducted a three‐year experiment to examine the consequences for CO₂ exchange of advanced spring green‐up and altered timing of grazing by migratory Pacific black brant in a coastal wetland in western Alaska. Experimental treatments represent the variation in green‐up and timing of peak grazing intensity that currently exists in the system. Delayed grazing resulted in greater net ecosystem exchange (NEE) and gross primary productivity (GPP), while early grazing reduced CO₂ uptake with the potential of causing net ecosystem carbon (C) loss in late spring and early summer. Conversely, advancing the growing season only influenced ecosystem respiration (ER), resulting in a small increase in ER with no concomitant impact on GPP or NEE. The experimental treatment that represents the most likely future, with green‐up advancing more rapidly than arrival of migratory geese, results in NEE changing by 1.2 µmol m^?2 s^?1 toward a greater CO₂ sink in spring and summer. Increased sink strength, however, may be mitigated by early arrival of migratory geese, which would reduce CO₂ uptake. Importantly, while the direct effect of climate warming on phenology of green‐up has a minimal influence on NEE, the indirect effect of climate warming manifest through changes in the timing of peak grazing can have a significant impact on C balance in northern coastal wetlands. Furthermore, processes influencing the timing of goose migration in the winter range can significantly influence ecosystem function in summer habitats.     

Fasting-Mimicking Diet Modulates Microbiota and Promotes Intestinal Regeneration to Reduce Inflammatory Bowel Disease Pathology

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Spring and summer microhabitat use by Schlegel’s Japanese gecko,Gekko japonicus (Reptilia: Squamata: Gekkonidae), in urban areas

Differential microhabitat use may be beneficial to achieving fitness in seasonally variable environmental conditions. To explore whether the microhabitat use of the nocturnal Schlegel’s Japanese gecko, Gekko japonicus, varies seasonally and depends on juvenile, male, and female reproductive groups, we investigated five categorical and five quantitative measure variables of microhabitat use in a wild population both in spring and summer. Most geckos were found on white, vertical planes of concrete and plastered brick walls. None of the categorical variables (type of location, substrate, substrate color, light source, and refuge) significantly differed according to season or group, while substrate temperature and irradiance at the location where geckos were observed and the distance from the nearest potential refuge were significantly greater in summer than in spring. The quantitative measure variables did not differ among the reproductive groups. These results suggest that G. japonicus seasonally adjusts its microhabitat use mainly in terms of quantitative measure variables rather than categorical variables.     

MsSAMS,a cold stress-responsive gene,provides resistance to environmental stress in T2-generation transgenic plants

The SAMS (S-adenosylmethionine synthetase) gene is known to play an important role in the mechanism of cold resistance, as overexpression of this gene results in phenotypic changes in T₁-generation transgenic plants. Accordingly, this study was conducted to test the expression of the MsSAMS gene in T₂-generation transgenic plants and to investigate the resistance of these plants and the function of the transgene in response to various environmental stresses. For the morphological analysis of T₂-generation transgenic plants overexpressing the MsSAMS gene, observations using scanning electron microscopy (SEM) were performed. T₂-generation transgenic plants were obtained by planting a total of 5 lines, and their characteristics were tested by comparisons with those of the control. SEM revealed that the thickest leaves were produced by the T6 transgenic line—161.24?±?8.05 µm. The number of stomata ranged from 20.00?±?2.65 to 34.00?±?1.00 in the T₂-generation transgenic plants, but the control had more stomata. Resistance to various factors, such as low temperature, drought, and oxidative stress, in the T₂-generation transgenic plants was also confirmed. Under cold-stress conditions, the T6 transgenic line presented the lowest value (22.73%) of ion leakage, and under drought-stress conditions, compared with the control, the transgenic lines presented lower ion leakage after being treated with various concentrations of mannitol. Even under oxidative-stress conditions, the T₂-generation transgenic plants presented ion leakage levels that were 32.91?±?4.24 to 48.33?±?3.54% lower than those of the control after treatment with various concentrations of methyl viologen. Regarding SAMS enzyme activity, as the duration of cold treatment increased, the activity in the transgenic plants tended to decrease and then increase. During 48 h of cold treatment, the control showed a decrease in SAM content, while the T₂-generation transgenic plants presented an increase in SAM content, from 13.58?±?1.04 to 22.75?±?1.95 mg protein/g FW. The results suggest that the MsSAMS gene may be important to the mechanisms of resistance to oxidative and drought stresses in addition to its previously known association with cold resistance. Based on these results, it was suggested that the MsSAMS gene, whose expression is induced by cold stress, can serve as a marker of various responses to environmental stresses, because resistance to cold damage and various environmental stresses are stably inherited in the T₂ generation.

     

Physiological activity of E. coli engineered to produce butyric acid

Faecalibacterium prausnitzii (F. prausnitzii) is one of the most abundant bacteria in the human intestine, with its anti-inflammatory effects establishing it as a major effector in human intestinal health. However, its extreme sensitivity to oxygen makes its cultivation and physiological study difficult. F. prausnitzii produces butyric acid, which is beneficial to human gut health. Butyric acid is a short-chain fatty acid (SCFA) produced by the fermentation of carbohydrates, such as dietary fibre in the large bowel. The genes encoding butyryl-CoA dehydrogenase (BCD) and butyryl-CoA:acetate CoA transferase (BUT) in F. prausnitzii were cloned and expressed in E. coli to determine the effect of butyric acid production on intestinal health using DSS-induced colitis model mice. The results from the E. coli Nissle 1917 strain, expressing BCD, BUT, or both, showed that BCD was essential, while BUT was dispensable for producing butyric acid. The effects of different carbon sources, such as glucose, N-acetylglucosamine (NAG), N-acetylgalactosamine (NAGA), and inulin, were compared with results showing that the optimal carbon sources for butyric acid production were NAG, a major component of mucin in the human intestine, and glucose. Furthermore, the anti-inflammatory effects of butyric acid production were tested by administering these strains to DSS-induced colitis model mice. The oral administration of the E. coli Nissle 1917 strain, carrying the expression vector for BCD and BUT (EcN-BCD-BUT), was found to prevent DSS-induced damage. Introduction of the BCD expression vector into E. coli Nissle 1917 led to increased butyric acid production, which improved the strain’s health-beneficial effects.     

Effects of myeloid sirtuin 1 deficiency on hypothalamic neurogranin in mice fed a high-fat diet

Hypothalamic inflammation has been known as a contributor to high-fat diet (HFD)-induced insulin resistance and obesity. Myeloid-specific sirtuin 1 (SIRT1) deletion aggravates insulin resistance and hypothalamic inflammation in HFD-fed mice. Neurogranin, a calmodulin-binding protein, is expressed in the hypothalamus. However, the effects of myeloid SIRT1 deletion on hypothalamic neurogranin has not been fully clarified. To investigate the effect of myeloid SIRT1 deletion on food intake and hypothalamic neurogranin expression, mice were fed a HFD for 20 weeks. Myeloid SIRT1 knockout (KO) mice exhibited higher food intake, weight gain, and lower expression of anorexigenic proopiomelanocortin in the arcuate nucleus than WT mice. In particular, KO mice had lower ventromedial hypothalamus (VMH)-specific neurogranin expression. However, SIRT1 deletion reduced HFD-induced hypothalamic neurogranin. Furthermore, hypothalamic phosphorylated AMPK and parvalbumin protein levels were also lower in HFD-fed KO mice than in HFD-fed WT mice. Thus, these findings suggest that myeloid SIRT1 deletion affects food intake through VMH-specific neurogranin-mediated AMPK signaling and hypothalamic inflammation in mice fed a HFD.     

Pleiotrophin inhibits melanogenesis via Erk1/2‐MITF signaling in normal human melanocytes

Pleiotrophin (PTN) is a secreted heparin‐binding protein that is involved in various biological functions of cell growth and differentiation. Little is known about the effects of PTN on the melanocyte function and skin pigmentation. In this study, we investigated whether PTN would affect melanogenesis. PTN was expressed in melanocytes and fibroblasts of human skin. Transfection studies revealed that PTN decreased melanogenesis, probably through MITF degradation via Erk1/2 activation in melanocytes. The inhibitory action of PTN in pigmentation was further confirmed in ex vivo cultured skin and in the melanocytes cocultured with fibroblasts. These findings suggest that PTN is a crucial factor for the regulation of melanogenesis in the skin.