Study of interaction between citrate-coated silver nanoparticles and gamma globulin using spectroscopic method

Communicated by Ramaswamy H. Sarma     

Growth characteristics of Adiantum reniforme var. sinensis and A. capillus‐veneris in response to light and soil moisture

Adiantum reniforme var. sinensis (Adiantaceae) is an endangered fern endemic to the Three Gorges region in southwest China. To elucidate possible ecophysiological mechanisms restricting its distribution, effects of the availability of light (28%, 14% and 7% of open field) and soil moisture (60% and 40% of field capacity) on dry matter production and allocation, leaf morphology and water use efficiency (WUE) were examined in A. reniforme var. sinensis and its widespread congener A. capillus‐veneris. Both species had lower root/shoot ratio (R/S) and higher specific leaf area (SLA) when grown at low light. However, A. reniforme var. sinensis showed less plasticity for total leaf area (LA) and leaf area ratio (LAR) than A. capillus‐veneris, and its root mass, total mass and WUE decreased as light availability decreased. Under water stress, all traits of both species except WUE were significantly affected. However, drought stress decreased total mass of A. capillus‐veneris but did not have a significant effect on A. reniforme var. sinensis. Compared with A. capillus‐veneris, A. reniforme var. sinensis had significantly higher R/S but lower values for other analyzed traits. These results suggest that A. reniforme var. sinensis is relatively superior in drought tolerance but inferior at low light, allowing it to persist in habitats with low soil moisture and high light availability but with few coexisting species present.     

Hepatic SREBP-2 and cholesterol biosynthesis are regulated by FoxO3 and Sirt6

Cholesterol homeostasis is crucial for cellular function and organismal health. The key regulator for the cholesterol biosynthesis is sterol-regulatory element binding protein (SREBP)-2. The biochemical process and physiological function of SREBP-2 have been well characterized; however, it is not clear how this gene is epigenetically regulated. Here we have identified sirtuin (Sirt)6 as a critical factor for Srebp2 gene regulation. Hepatic deficiency of Sirt6 in mice leads to elevated cholesterol levels. On the mechanistic level, Sirt6 is recruited by forkhead box O (FoxO)3 to the Srebp2 gene promoter where Sirt6 deacetylates histone H3 at lysines 9 and 56, thereby promoting a repressive chromatin state. Remarkably, Sirt6 or FoxO3 overexpression improves hypercholesterolemia in diet-induced or genetically obese mice. In summary, our data suggest an important role of hepatic Sirt6 and FoxO3 in the regulation of cholesterol homeostasis.     

High-Efficiency Thermal Asymmetric Interlaced PCR (hiTAIL-PCR) for Determination of a Highly Degenerated Prophage WO Genome in a Wolbachia Strain Infecting a Fig Wasp Species

Temperate bacteriophage WO is a model system for studying tripartite interactions among viruses, bacteria, and eukaryotes, especially investigations of the genomic stability of obligate intracellular bacteria. Few WO genomes exist because of the difficulty in isolating viral DNA from eukaryotic hosts, and most reports are by-products of Wolbachia sequencing. Only one partial genome of a WO phage has been determined directly from isolated particles. We determine the complete genome sequence of prophage WO (WOSol) in Wolbachia strain wSol, which infects the fig wasp Ceratosolen solmsi (Hymenoptera: Chalcidoidea), by high-efficiency thermal asymmetric interlaced PCR. The genome of WOSol is highly degenerated and disrupted by a large region (14,267 bp) from Wolbachia. Consistent with previous molecular studies of multiple WO genomes, the genome of WOSol appears to have evolved by single nucleotide mutations and recombinations.     

Increasing oxidative stress tolerance and subculturing stability of Cordyceps militaris by overexpression of a glutathione peroxidase gene

Like other filamentous fungi, the medicinal ascomycete Cordyceps militaris frequently degenerates during continuous maintenance in culture by showing loss of the ability to reproduce sexually or asexually. Degeneration of fungal cultures has been related with cellular accumulation of reactive oxygen species (ROS). In this study, an antioxidant glutathione peroxidase (Gpx) gene from Aspergillus nidulans was engineered into two C. militaris strains, i.e., the Cm01 strain which can fruit normally and the Cm04 strain which has lost the ability to form fruiting bodies on different media through subculturing. The results showed that the mitotically stable mutants had higher Gpx activities and stronger capacity to scavenge cellular ROS than their parental strains. Most significantly, the fruiting ability of Cm04 strain was restored by overexpression of the antioxidant enzyme. However, after being successively transferred for up to ten generations, two of three Cm04 mutants again lost the ability to fruit on insect pupae while Cm01 transformants remained fertile. This study confirms the relationship between fungal culture degeneration and cellular ROS accumulation. Our results indicate that genetic engineering with an antioxidant gene can be an effective way to reverse fungal degeneration during subculturing.     

Discovery of a potent respiratory syncytial virus RNA polymerase inhibitor

Targeting viral polymerases has been a proven and attractive strategy for antiviral drug discovery. Herein we describe our effort in improving the antiviral activity and physical properties of a series of benzothienoazepine compounds as respiratory syncytial virus (RSV) RNA polymerase inhibitors. The antiviral activity and spectrum of this class was significantly improved by exploring the amino substitution of the pyridine ring, resulting in the discovery of the most potent RSV A polymerase inhibitors reported to date.     

Circadian Yin-Yang Regulation and Its Manipulation to Globally Reprogram Gene Expression

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Glutamate transporter type 3 knockout leads to decreased heart rate possibly via parasympathetic mechanism

Parasympathetic tone is a dominant neural regulator for basal heart rate. Glutamate transporters (EAAT) via their glutamate uptake functions regulate glutamate neurotransmission in the central nervous system. We showed that EAAT type 3 (EAAT3) knockout mice had a slower heart rate than wild-type mice when they were anesthetized. We design this study to determine whether non-anesthetized EAAT3 knockout mice have a slower heart rate and, if so, what may be the mechanism for this effect. Young adult EAAT3 knockout mice had slower heart rates than those of their littermate wild-type mice no matter whether they were awake or anesthetized. This difference was abolished by atropine, a parasympatholytic drug. Carbamylcholine chloride, a parasympathomimetic drug, equally effectively reduced the heart rates of wild-type and EAAT3 knockout mice. Positive immunostaining for EAAT3 was found in the area of nuclei deriving fibers for vagus nerve. There was no positive staining for the EAATs in the sinoatrial node. These results suggest that EAAT3 knockout mice have a slower heart rate at rest. This effect may be caused by an increased parasympathetic tone possibly due to increased glutamate neurotransmission in the central nervous system. These findings indicate that regulation of heart rate, a vital sign, is one of the EAAT biological functions.