BIODIVERSITY PATTERN AND CONSERVATION OF AQUATIC VASCULAR PLANTS IN THE YANGTZE RIVER BASIN,CHINA北大核心CSCD

The Yangtze River is the largest river in China. It is a priority conservation area for biodiversity of the world, with its main river, branches and wetlands. As an essential part of freshwater ecosystem, aquatic vegetation has been well studied by Chinese researchers since 1950s, but large-scaled analysis on the biodiversity pattern is lacked. Based on published studies, we analyzed spatial and temporal pattern of aquatic plant diversity in the Yangtze River Basin, and calculated the suitable habitat area and underlying influence of environmental factors using MaxEnt software. A total of 298 species are recognized, belonging to 121 genera in 52 families, which is 57.6% of the total aquatic vascular plants in China. The Yangtze River Basin is the key area for aquatic plant diversity of China, especially the subregions of middle reaches. The elevation and land use are the key environmental variables to the spatial pattern of aquatic plants. The separation among water systems have weak influence on the spatial pattern of diversity in aquatic vascular plants, but potamo-lacustrine habitats facilitated the species homogenization of the flora in a sub-basin scale. The network consists of Poyang Lake, Dongting Lake, Tai Lake, and the middle and lower mainstream is the suitable area for the aquatic plants based on the MaxEnt model. In the past half century, the decline or loss of aquatic vegetation occurred in plenty of lakes in the Yangtze River Basin. We suggested that the protection of aquatic vegetation should be incorporated into the integrated conservation of the middle and lower Yangtze River. © 2019, Institute of Hydrobiology, Chinese Academy of Sciences. All rights reserved.     

THE DISTRIBUTION AND ACCUMULATION OF SELENIUM IN ROOTS AND SHOOTS OF PLANTS NATURALLY GROWN IN THE SOILS OF KEBAN’S PB-ZN-F MINING AREA,TURKEY

The objective of this study is to determine the distribution factors and enrichment coefficients between soil and plant parts by studying the accumulation and distribution of selenium (Se) in the roots and shoots of different plants. The plants (9 samples of Euphorbia macroclada, 5 samples of Verbascum cheiranthifolium, 8 samples of Astragalus gummifer) and their associated soil samples were collected from the Keban mining area. The roots and the shoots of these plants, together with the associated soils, were analyzed by ICP-MS. The mean Se value of the contaminated surface soils was found to be two to five times higher than those of previously studied uncontaminated surface soils. Se concentrations of the plant parts were lower than those in their associated alkaline soils, where the plants were grown, except for in the shoots of A. gummifer. Mean Se concentrations in the roots of E. macroclada, V. cheiranthifolium, and A. gummifer were 0.82, 0.22, and 0.47 mg kg^?1 on a dry weight basis, respectively, while Se concentrations were 0.29, 0.26, and 2.66 mg kg^?1 in the shoots on a dry weight basis, respectively. The enrichment coefficients and the distribution factors of those plants were lower than 1, except for the distribution factors of V. cheiranthifolium and A. gummifer plants. Thus, it appeared that the shoots of these plants could make them efficient bioaccumulator plants for Se because of high distribution factors and enrichment coefficients. Due to such factors, they can also be used to clean or rehabilitate soils and areas contaminated with Se.     

DIURNAL,AGE, AND IMMUNE REGULATION OF INTERLEUKIN-1β AND INTERLEUKIN-1 TYPE 1 RECEPTOR IN THE MOUSE SUPRACHIASMATIC NUCLEUS

Circadian clocks serve to impose a near-24-h temporal architecture on an organism's physiology, metabolism, and behavior. In mammals, the suprachiasmatic nucleus (SCN) of the hypothalamus functions as the master circadian pacemaker. There is growing evidence that immunomodulators, such as cytokines, may impinge on circadian timekeeping. We examined whether there is endogenous expression of the proinflammatory cytokine interleukin-1β (IL-1β) and its signaling receptor IL-1R1 in the SCN of young and older mice across the diurnal cycle. We found expression of both IL-1β and IL-1R1 in the young SCN, although only IL-1R1 displayed temporal regulation. In the older SCN, levels of IL-1β were expressed at lower levels than in the young SCN, and IL-1R1 did not vary across the 24?h. We also report age-related day-night variation of IL-1β and IL-1R1 in the paraventricular nucleus (PVN) of the hypothalamus. Further, we examined the effect of peripheral immune challenge on IL-1β and IL-1R1 in the SCN. We found that IL-1β immunoreactivity was not altered 6 or 24?h after a septic dose of lipopolysaccharide (LPS; 5?mg/kg), whereas IL-1R1 was significantly up-regulated in the SCN both 6 and 24?h after LPS. We also demonstrate cellular activation in the SCN 24?h following LPS treatment, as evidenced by increased c-Fos and p65-NF-κB (nuclear factor kappa B) expression. Our results indicate that IL-1β and its associated signaling system may play a role in mediating the response of the circadian timing system to immune challenge as well as potentially contributing to the basal functioning of the SCN clock. (Author correspondence: andrew.coogan@nuim.ie)     

IS THE PREDOMINANT PERIOD OF CELL ARREST AND PRESENCE OF ENDOREDUPLICATED CELLS COINCIDENT WITH PRODUCTION OF SECONDARY VASCULAR TISSUES IN INTACT AND CULTURED ROOTS OF RAPHANUS SATIVUS L.?

Experimental results show that predominant cell arrest in G2 and the presence of endoreduplicated cells are coincident with presence of secondary vascular tissues while preponderant cell arrest in G1 and absence of polyploid cells are coincident with an absence of secondary vascular tissues in mature root tissues of intact and cultured roots of Raphanus sativus L. In mature tissues of intact seedling roots, most cells arrest in G2, and both polyploid cells and secondary vascular tissues are present. If excised roots are grown on simple medium, most mature cells arrest in G1, none undergo endoreduplication, and only primary vascular tissues are present. When bases of these excised roots are later placed in a medium with auxin, cytokinin, and myo-inositol that produces secondary vascular tissues in vitro, preponderant cell arrest occurred in G2 with some polyploid cells. The general relationship of predominant period of cell arrest, presence of polyploid cells, and presence of secondary vascular tissues in mature roots among plants of various taxa is surveyed.     

AUXIN,AN ENDOGENOUS REGULATOR OF GROWTH IN ALGAE?1,2

The effects of 5 pairs of synthetic auxins and chemically related, but biologically inactive, derivatives (e.g., 2,4- and 3,5-dichlorophenoxyacetic acid, respectively) on blade growth of the brown alga, Alaria esculenta (L.) Grev.(Laminariales) were studied. The significant result was the inability to divide the growth responses into auxin and non-auxin groups. At high concentrations (10^?3 M) 9 test substances inhibited blade growth; lower concentrations (<10^?3 M) were either slightly inhibitory or showed no effect. The data suggest that a higher plant auxin-specific recognition mechanism is lacking in this alga. As this mechanism is central to higher plant concepts of growth control by auxin, the role of auxin as an endogenous regulator of growth in Alaria, and perhaps other algae as well, seems unlikely. This interpretation is consistent with recent negative biochemical data from auxin binding studies using subcellular preparations from algae.     

DO RECENT FINDINGS IN PLANT MITOCHONDRIAL MOLECULAR AND POPULATION GENETICS HAVE IMPLICATIONS FOR THE STUDY OF GYNODIOECY AND CYTONUCLEAR CONFLICT?

The coexistence of females and hermaphrodites in plant populations, or gynodioecy, is a puzzle recognized by Darwin. Correns identified cytoplasmic inheritance of one component of sex expression, now known as cytoplasmic male sterility (CMS). Lewis established cytonuclear inheritance of gynodioecy as an example of genetic conflict. Although biologists have since developed an understanding of the mechanisms allowing the joint maintenance of CMS and nuclear male fertility restorer genes, puzzles remain concerning the inheritance of sex expression and mechanisms governing the origination of CMS. Much of the theory of gynodioecy rests on the assumption of maternal inheritance of the mitochondrial genome. Here we review recent studies of the genetics of plant mitochondria, and their implications for the evolution and transmission of CMS. New studies of intragenomic recombination provide a plausible origin for the chimeric ORFs that characterize CMS. Moreover, evidence suggests that nonmaternal inheritance of mitochondria may be more common than once believed. These findings may have consequences for the maintenance of cytonuclear polymorphism, mitochondrial recombination, generation of gynomonoecious phenotypes, and interpretation of experimental crosses. Finally we point out that CMS can alter the nature of the cytonuclear conflict that may have originally selected for uniparental inheritance.     

THE ISSUE OF ANTIBIOTIC USE IN THE LIVESTOCK INDUSTRY: WHAT HAVE WE LEARNED?

It is generally believed that it is better to use medicinal products as therapeutics to treat disease situations, using high doses for short periods of time, rather than as prophylactics, when low doses are fed continuously. It is therefore the continuous use of low levels of medicinal products as growth promoters in farm animals that has been brought into question, as it is thought that this may increase the risk of development of bacterial resistance to antibiotics used as therapeutic drugs to treat disease in humans.     

SYNTHESIS AND IN VITRO ANTI-HCV ACTIVITY OF β-D- and L-2′-DEOXY-2′-FLUORORIBONUCLEOSIDES

Based on the discovery of β-D-2′-deoxy-2′-fluorocytidine as a potent anti-hepatitis C virus (HCV) agent, a series of β-D- and l-2′-deoxy-2′-fluororibonucleosides with modifications at 5 and/or 4 positions were synthesized and evaluated for their in vitro activity against HCV and bovine viral diarrhea virus (BVDV). The introduction of the 2′-fluoro group was achieved by either fluorination of 2,2′-anhydronucleosides with hydrogen fluoride-pyridine or potassium fluoride, or a fluorination of arabinonucleosides with DAST. Among the 27 analogues synthesized, only the 5-fluoro compounds, namely β-D-2′-deoxy-2′,5-difluorocytidine (5), had anti-HCV activity in the subgenomic HCV replicon cell line, and inhibitory activity against ribosomal RNA. As β-D-N4-hydroxycytidine (NHC) had previously shown potent anti-HCV activity, the two functionalities of the N4-hydroxyl and the 2′-fluoro were combined into one molecule, yielding β-D-2′-deoxy-2′-fluoro-N4-hydroxycytidine (12). However, this nucleoside showed neither anti-HCV activity nor toxicity. All the l-forms of the analogues were devoid of anti-HCV activity. None of the compounds showed anti-BVDV activity, suggesting that the BVDV system cannot reliably predict anti-HCV activity in vitro.     

INFLUENCE OF pH AND TEMPERATURE ON THE ACTIVITY OF SnO2-BOUND α-AMYLASE: A GENOTOXICITY ASSESSMENT OF SnO2 NANOPARTICLES

Immobilization of biologically important molecules on a myriad of nanosized materials has attracted great attention due to their small size, biocompatibility, higher surface-to-volume ratio, and lower toxicity. These properties make nanoparticles (NPs) a superior matrix over bulk material for the immobilization of enzymes and proteins. In the present study, Bacillus amyloliquefaciens α-amylase was immobilized on SnO₂ nanoparticles by a simple adsorption mechanism. Nanoparticle-adsorbed enzyme retained 90% of the original enzyme activity. Thermal stability of nanosupport was investigated by thermogravimetric and differential thermal analysis. Scanning electron microscopic studies showed that NPs have porous structure for the high-yield immobilization of α-amylase. The genotoxicity of SnO₂-NPs was analyzed by pUC¹⁹ plasmid nicking and comet assay and revealed that no remarkable DNA damage occurred in lymphocytes. The pH-optima was found to be the same for both free and SnO₂-NPs bound enzyme, while the temperature-optimum for NPs-adsorbed α-amylase was 5°C higher than its free counterpart. Immobilized enzyme retained more than 70% enzyme activity even after its eight repeated uses.     

THE MARINE TOXIN OKADAIC ACID REDUCES O2− GENERATION AND TYROSINE PHOSPHORYLATION IN LPS-PRIMED RAT NEUTROPHILS

Contrasting effects of okadaic acid (OKA) on neutrophil (PMN) superoxide anion (O₂⁻) generation have been reported. In this study, we examined the effect of OKA on phorbol myristate acetate (PMA)-stimulated O₂⁻ generation in rat PMNs primed with LPS in vivo (LPS-PMN) and saline-treated rat PMNs (SAL-PMN). The following results were observed: (1) OKA, but neither genistein nor vanadate, markedly reduced O₂⁻ generation in a dose and time-dependent manner; (2) genistein, a tyrosine kinase inhibitor, as well as OKA, reduced tyrosine phosphorylation; (3) sodium orthovanadate, a tyrosine phosphatase inhibitor, potently enhanced tyrosine phosphorylation. Our studies suggest that OKA might reduce tyrosine phosphorylation by affecting the activity of tyrosine phosphatases regulated by serine-threonine phosphorylation. © 1997 Elsevier Science Inc.