Ordered spatial configuration protects representations of dissimilar items and reduces the similarity effect in visual working memory.

Although similarity could improve visual working memory (VWM) performance, it remains unclear how the spatial configuration of visual information influences the similarity effect in VWM. We explored this question by manipulating the orderliness of spatial configuration (ordered vs. scrambled) in the simultaneous (Experiment 1) and sequential (Experiment 2) change detection tasks. The results showed that similarity improved VWM performance when memory items were presented simultaneously and sequentially. For the simultaneous memory array containing similar and dissimilar items, the performance of the ordered spatial configuration was better than that of the scrambled spatial configuration when probing dissimilar items, while no such difference was found when probing similar items. Further, the similarity effect value in the scrambled spatial configuration was higher than that in the ordered spatial configuration. For the sequential memory array containing similar and dissimilar items, spatial configuration did not affect the similarity effect in VWM. Taken together, these findings suggest that spatial configuration could modulate the similarity effect when memory items are presented simultaneously, in which the ordered spatial configuration protects representations of dissimilar items and reduces the similarity effect in VWM. Our study provides additional evidence for the role of spatial configuration in the similarity effect in VWM, and supports the hierarchical model.

Cold adaptation in drylands: transcriptomic insights into cold-stressed Nostoc flagelliforme and characterization of a hypothetical gene with cold and nitrogen stress tolerance.

Environmental stressors, especially low temperature, are very common on the earth's dryland systems. Terrestrial cyanobacteria have evolved with cold adaptability in addition to extreme dryness and high irradiation resistance. The dryland soil surface-dwelling species, Nostoc flagelliforme, serves as a potential model organism to gain insights into cyanobacterial cold adaptation. In this study, we performed transcriptomic analysis of N. flagelliforme samples in response to low temperature. The results revealed that the biological processes, such as terpenoid biosynthetic process, oxidoreductase activity, carbohydrate metabolism, biosynthesis of secondary metabolites, lipid and nitrogen metabolism, were significantly and dynamically changed during the cold stress. It was noteworthy that the transcription of the denitrification pathway for ammonia accumulation was enhanced, implying an importance for nitrogen utilization in stress resistance. In addition, characterization of a cold-responsive hypothetical gene csrnf1 found that it could greatly improve the cold-resistant performance of cells when it was heterologously expressed in transgenic Nostoc sp. PCC 7120. It was also found that csrnf1 transgenic strain exhibited resistance to nitrogen-deficient environmental stress. Considering that dryland cyanobacteria have to cope with low temperature on infertile soils, this study would enrich our understanding on the importance of multifunction of the genes for environmental cold adaptation in drylands.

Improved production of echinenone and canthaxanthin in transgenic Nostoc sp. PCC 7120 overexpressing a heterologous crtO gene from Nostoc flagelliforme.

Echinenone and canthaxanthin are important carotenoid pigments with food and industrial applications. Biosynthesis of echinenone and/or canthaxanthin is catalyzed by ß-carotene ketolase (CrtO), with ß-carotene as the substrate. In this study, we generated transgenic Nostoc sp. PCC 7120 overexpressing a heterologous crtO gene from Nostoc flagelliforme and evaluated the productivity of both pigments. Normal (BG11 medium, 30 °C) and osmotic stress (BG11 medium supplemented with 0.4 M mannitol, 30 °C) conditions were used for cultivation. As compared to control strain, production of echinenone and canthaxanthin in transgenic strain were respectively increased by more than 16 % and 80 %, under either normal or osmotic stress conditions. Especially upon the stress condition, higher proportion of echinenone and canthaxanthin in total pigments was achieved, which should be beneficial for downstream separation and purification. In addition, transgenic strain showed drought tolerance and could revive from desiccation treatment after rewetting. Thus, this study provided technical clues for production of both pigments in engineered cyanobacteria as well as for cyanobacterial anhydrobiotic engineering.

The effects of the exopolysaccharide and growth rate on the morphogenesis of the terrestrial filamentous cyanobacterium Nostoc flagelliforme.

The terrestrial cyanobacterium Nostoc flagelliforme, which contributes to carbon and nitrogen supplies in arid and semi-arid regions, adopts a filamentous colony form. Owing to its herbal and dietary values, this species has been overexploited. Largely due to the lack of understanding on its morphogenesis, artificial cultivation has not been achieved. Additionally, it may serve as a useful model for recognizing the morphological adaptation of colonial cyanobacteria in terrestrial niches. However, it shows very slow growth in native habitats and is easily disintegrated under laboratory conditions. Thus, a novel experimental system is necessary to explore its morphogenetic mechanism. Liquid-cultured N. flagelliforme has been well developed for exopolysaccharide (EPS) production, in which microscopic colonies (micro-colonies) are generally formed. In this study, we sought to gain some insight into the morphogenesis of N. flagelliforme by examining the effects of two external factors, the EPS and environmental stress-related growth rate, on the morphological shaping of micro-colonies. Our findings indicate that the EPS matrix could act as a basal barrier, leading to the bending of trichomes during their elongation, while very slow growth is conducive to their straight elongation. These findings will guide future cultivation and application of this cyanobacterium for ecological improvement.

Flexibility-Rigidity Coordination of the Dense Exopolysaccharide Matrix in Terrestrial Cyanobacteria Acclimated to Periodic Desiccation.

A dense exopolysaccharide (EPS) matrix is crucial for cyanobacterial survival in terrestrial xeric environments, in which cyanobacteria undergo frequent expansion and shrinkage processes during environmental desiccation-rehydration cycles. However, it is unclear how terrestrial cyanobacteria coordinate the structural dynamics of the EPS matrix upon expansion and shrinkage to avoid potential mechanical stress while benefiting from the matrix. In the present study, we sought to answer this question by investigating the gene expression, protein dynamics, enzymatic characteristics, and biological roles of WspA, an abundantly secreted protein, in the representative terrestrial cyanobacterium Nostoc flagelliforme The results demonstrated that WspA is a novel ß-galactosidase that facilitates softening of the EPS matrix by breaking the polysaccharide backbone under substantial moisture or facilitates the thickening and relinkage of the broken matrix during the drying process, and thus these regulations are well correlated with moisture availability or desiccation-rehydration cycles. This coordination of flexibility and rigidity of the cyanobacterial extracellular matrix may contribute to a favorable balance of cell growth and stress resistance in xeric environments.IMPORTANCE How the exopolysaccharide matrix is dynamically coordinated by exoproteins to cope with frequent expansion and shrinkage processes in terrestrial colonial cyanobacteria remains unclear. Here we elucidated the biochemical identity and biological roles of a dominant exoprotein in these regulation processes. Our study thus gained insight into this regulative mechanism in cyanobacteria to combat periodic desiccation. In addition, the filamentous drought-adapted cyanobacterium Nostoc flagelliforme serves as an ideal model for us to explore this issue in this study.

Rare single-molecule magnets with six-coordinate Ln(III) ions exhibiting a trigonal antiprism configuration.

Four Ni-Ln-Ni heterometallic complexes, [Ni2LnL2]NO3·3H2O (H3L = tri(((3-methoxysalicylidene)amino)ethyl)amine, Ln = Gd for , Tb for and Dy for , respectively) and [Ni2DyL2]ClO4·MTBE·0.65H2O (, MTBE = methyl tert-butyl ether) have been synthesized by diffusion of methyl tert-butyl ether vapor into the reaction solution. The X-ray analyses demonstrated that the Gd(III) ion in exhibits rare seven-coordination, the Tb(III) and Dy(III) ions in display unusual six-coordination, and two Ni(II) ions and one Ln(III) ion are bridged by six phenolato atoms to form linear Ni-Ln-Ni heterotrinuclear complexes for . All complexes exhibit weak ferromagnetic interactions between Ni(II) and Ln(III) ions. Alternating current susceptibility measurements demonstrated that compounds and behave as single-molecule magnets with the effective energy barriers of 14.17 and 11.13 K under zero direct current field. They are rare single-molecule magnets containing six-coordinate Dy(III) ions.

[Effect of Magnesium Sulfate, Nifedipine Tablet Combined Salvia Injection on ET-1/NO, TXA2/PGI2 and Hemorheology of Preeclampsia Patients].

OBJECTIVE: To observe the effect of magnesium sulfate, Nifedipine Tablet (NT) combined Salvia Injection (SI) on endothelin-1 (ET-1), nitric oxide (NO), thromboxane A2(TXA2), prostacyclin I2(PG2), and hemorheology of preeclampsia patients. METHODS: Totally 704 preeclampsia patients were randomly assigned to the treatment group and the control group, 352 cases in each group. All patients were treated with magnesium sulfate combined NT (on the first day: slow intravenous injection of magnesium sulfate 5 g + intravenous dripping of magnesium sulfate injection 10 g + oral administration of NT 30 mg; on the second and third day, intravenous dripping of magnesium sulfate injection 10 g + oral administration of NT 30 mg), while those in the treatment group were dripped with SI additionally at 20 mL per day for 3 consecutive days. Before and after treatment plasma levels of endothelin-1 (ET-1), nitric oxide (NO), TXA2, PGi2, and hemorheology indicators [such as high blood viscosity (HBV), low blood viscosity (LBV), plasma viscosity (PV), erythrocyte rigidity index (ERI), fibrinogen (FIB)] of two groups were detected. RESULTS: Compared with the same group before treatment, serum levels of ET-1, TXA2, HBV, LBV, PV, ERI, and FIB decreased in the two groups after treatment (P <0. 05), but levels of NO and PG2 increased (P <0. 05). Compared with the control group in the same period, levels of ET-1, TXA2, HBV, LBV, PV, ERI, and FIB decreased in the treatment group after treatment (P <0. 05), but levels of NO and PGI2 increased (P <0. 05). CONCLUSION: Magnesium sulfate, NT combined SI could effectively regulate the balance of ET-1/NO and TXA2/PGI2, and improve hemorheology of preeclampsia patients.

Effects of puerarin on pulmonary vascular remodeling and protein kinase C-alpha in chronic cigarette smoke exposure smoke-exposed rats.

In order to investigate the effects of puerarin on pulmonary vascular remodeling and protein kinase C-alpha (PKC-alpha) in chronic exposure smoke rats, 54 male Wistar rats were randomly divided into 7 groups: control group (C group), smoke exposure groups (S4w group, S8w group), puerarin groups (P4w group, P8w group), propylene glycol control groups (PC4w group, PC8w group). Rats were exposed to cigarette smoke or air for 4 to 8 weeks. Rats in puerarin groups also received puerarin. To evaluate vascular remodeling, alpha-smooth muscle actin (alpha-SM-actin) staining was used to count the percentage of completely muscularised vessels to intraacinar pulmonary arteries (CMA/IAPA) which was determined by morphometric analysis of histological sections. Pulmonary artery smooth muscle cell (PASMC) apoptosis was detected by in situ end labeling technique (TUNEL), and proliferation by proliferating cell nuclear antigen (PCNA) staining. Reverse transcription-polymerase chain reaction (RT-PCR), immunofluorescence staining and Western blot analysis were done to detect the PKC-alpha mRNA and protein expression in pulmonary arteries. The results showed that in cigarette smoke-exposed rats the percentage of CMA/IAPA and alpha-SM-actin expression were increased greatly, PASMC apoptosis was increased and proliferation was markedly increased; Apoptosis indices (AI) and proliferation indices (PI) were higher than in C group; AI and PI were correlated with vascular remodeling indices; The expression of PKC-alpha mRNA and protein in pulmonary arteries was significantly higher than in C group. In rats treated with puerarin, the percentage of CMA/IAPA and cell proliferation was reduced, whereas PASMC apoptosis was increased; The expression levels of PKC-alpha mRNA and protein were lower than in smoke exposure rats. There was no difference among all these data between S groups and PC groups. These findings suggested that cigarette smoke-induced pulmonary vascular remodeling was most likely an effect of the imbalance of PASMC proliferation and apoptosis. Puerarin appears to be able to reduce cell proliferation and vascular remodeling possibly through PKC signaling transduction pathway.

Effects of Puerarin on Pulmonary Vascular Remodeling and Protein Kinase C-α in Chronic Cigarette Smoke Exposure Smoke-exposed Rats / 华中科技大学学报（医学）（英德文版）

In order to investigate the effects of puerarin on pulmonary vascular remodeling and protein kinase C-α (PKC-α) in chronic exposure smoke rats, 54 male Wistar rats were randomly di- vided into 7 groups: control group (C group), smoke exposure groups (S4w group, Saw group), puer- arin groups (P4w group, P8w group), propylene glycol control groups (PC4w group,PC8w group). Rats were exposed to cigarette smoke or air for 4 to 8 weeks. Rats in puerarin groups also received puer- arin. To evaluate vascular remodeling, alpha-smooth muscle actin (α-SM-actin) staining was used to count the percentage of completely muscularised vessels to intraacinar pulmonary arteries (CMA/IAPA) which was determined by morphometric analysis of histological sections. Pulmonary artery smooth muscle cell (PASMC) apoptosis was detected by in situ end labeling technique (TUNEL), and proliferation by proliferating cell nuclear antigen (PCNA) staining. Reverse transcrip- tion-polymerase chain reaction (RT-PCR), immunofluorescence staining and Western blot analysis were done to detect the PKC-α mRNA and protein expression in pulmonary arteries. The results showed that in cigarette smoke-exposed rats the percentage of CMA/IAPA and α-SM-actin expres- sion were increased greatly, PASMC apoptosis was increased and proliferation was markedly in- creased; Apoptosis indices (AI) and proliferation indices (PI) were higher than in C group; AI and PI were correlated with vascular remodeling indices; The expression of PKC-ct mRNA and protein in pulmonary arteries was significantly higher than in C group. In rats treated with puerarin, the per- eentage of CMA/IAPA and cell proliferation was reduced, whereas PASMC apoptosis was increased; The expression levels of PKC-α mRNA and protein were lower than in smoke exposure rats. There was no difference among all these data between S groups and PC groups. These findings suggested that cigarette smoke-induced pulmonary vascular remodeling was most likely an effect of the imbal- ance of PASMC proliferation and apoptosis. Puerarin appears to be able to reduce cell proliferation and vascular remodeling possibly through PKC signaling transduction pathway.

[Pulmonary vascular remodeling and protein kinase C-alpha expression in chronic smoke exposure and/or hypoxia rats].

OBJECTIVE: To investigate pulmonary vascular remodeling and protein kinase C-alpha (PKC-alpha) expression in chronic smoke exposure and/or hypoxia rats. METHODS: Fifty-six male Wistar rats were randomly divided into seven groups: control group (C group), smoke exposure groups (S(4W), S(8W) group), hypoxia groups (H(4W), H(8W) group), smoke exposure plus hypoxia groups (SH(4W), SH(8W) group). Wistar rats were exposed to cigarette smoke and/or hypoxia air [O2 (10.0 +/- 0.5)%] for 4 to 8 weeks. A method by right cardiac catheterization was used for measuring mean pulmonary artery pressure (mPAP). Right ventricle (RV), left ventricle (LV) plus interventricular septum (S) were split and weighed and right ventricular hypertrophy index (RVHI) was calculated. To evaluate vascular remodeling, alpha-smooth muscle actin (alpha-SM-actin) staining and count of the percentage of muscularized small pulmonary arteries which was determined by morphometric analysis of histological sections were used. Pulmonary artery smooth muscle cell (PASMC) apoptosis was detected by in situ end labeling technique (TUNEL), and proliferation by proliferating cell nuclear antigen (PCNA) staining. Reverse transcription-polymerase chain reaction (RT-PCR), immunofluorescence staining and Western blot analysis were used for the detection of PKC-alpha mRNA and protein expression in pulmonary arteries. RESULTS: mPAP in H(4W), H(8W), SH(4W), SH(8W) group [(31 +/- 7), (32 +/- 8), (32 +/- 9), (31 +/- 10) mm Hg, 1 mm Hg = 0.133 kPa] were higher than that in C group [(14 +/- 4) mm Hg, all P < 0.01], but mPAP in S(4W) and S(8W) group [(15 +/- 5), (16 +/- 6) mm Hg] were not increased (all P > 0.05). In S(4W), S(8W), H(4W), H(8W), SH(4W) and SH(8W) group, RVHI (0.258 +/- 0.024, 0.394 +/- 0.021, 0.374 +/- 0.020, 0.414 +/- 0.019, 0.434 +/- 0.023, 0.442 +/- 0.020, respectively), the percentage of muscularized arteries [(33.5 +/- 6.8)%, (41.1 +/- 9.8)%, (35.9 +/- 6.6)%, (46.0 +/- 6.3)%, (42.9 +/- 6.5)%, (50.2 +/- 9.9)%, respectively] and alpha-SM-actin expression (53 +/- 15, 75 +/- 14, 56 +/- 11, 82 +/- 17, 83 +/- 17, 98 +/- 16, respectively) were increased significantly (all P < 0.01). PASMC apoptosis was increased and proliferation was markedly increased. Apoptotic indices (AI, 2.5 +/- 1.0, 3.8 +/- 1.4, 2.3 +/- 1.1, 3.3 +/- 1.1, 3.5 +/- 1.4, 4.8 +/- 1.4, respectively) and proliferation indices (PI, 33.1 +/- 11.8, 43.8 +/- 11.0, 36.5 +/- 10.6, 46.3 +/- 12.1, 45.3 +/- 12.4, 53.3 +/- 13.4, respectively) were higher than those in C group (all P < 0.01). The expressions of PKC-alpha mRNA and protein were higher than those of C group (all P < 0.01). The differences were more significant between SH(4W) and H(4W) group, SH(8W) and H(8W) group (all P < 0.01). CONCLUSIONS: It is suggested that smoke is synergistic with hypoxia in aggravating pulmonary vascular remodeling. The possible mechanism is through PKC signaling transduction pathway activation.