Relationships between soil seed bank,vegetation and soil fertility along an urbanisation gradient

Questions: How does urbanisation influence soil mineral nitrogen stocks (nitrate and ammonium stocks) and what are the consequences of these modifications on the functional diversity of the herbaceous vegetation (vascular plants) and the seed bank? Location: Nine study sites were located on an urbanisation gradient in the city of Rennes, France. Methods: Three urbanisation levels were defined: urban areas (high grey/green ratio), suburban (medium grey/green ratio) and periurban (low grey/green ratio). For each urbanisation level, nitrates and ammonium stocks were quantified; the herbaceous vegetation was surveyed as well as the soil seed bank (using the seedling emergence method). Results: Nitrate concentration increased with urbanisation (the nitrate level in urban plots was twice the concentration in periurban ones) whereas the ammonium level was higher in periurban areas than in urban areas. In urban plots, the vegetation and the seed bank were more nitrophilous, whereas the nitrogen requirement was lower for periurban species. The relationship between the seed bank and the above‐ground vegetation was not significant. Conclusions: The higher nitrate concentration in the urban area appeared to be related to higher concentrations of atmospheric pollutants found in this area and lower ammonium levels may be related to the higher temperature in urban areas (leading to higher nitrification rates). The shift in the composition of the seed bank and vegetation appeared to be a consequence of higher nitrate stocks. The dissimilarity between the seed bank and vegetation may be caused by enhanced emergence of nitrophilous species in urban areas.     

Transducin Beta-Like Gene FTL1 Is Essential for Pathogenesis in Fusarium graminearum

Fusarium head blight caused by Fusarium graminearum is an important disease of wheat and barley. In a previous study, we identified several mutants with reduced virulence by insertional mutagenesis. A transducin beta-like gene named FTL1 was disrupted in one of these nonpathogenic mutants. FTL1 is homologous to Saccharomyces cerevisiae SIF2, which is a component of the Set3 complex involved in late stages of ascospore formation. The Δftl1 mutant was significantly reduced in conidiation and failed to cause typical disease symptoms. It failed to colonize the vascular tissues of rachis or cause necrosis on the rachis of inoculated wheat heads. The Δftl1 mutant also was defective in spreading from infected anthers to ovaries and more sensitive than the wild type to plant defensins MsDef1 and osmotin. However, the activation of two mitogen-activated protein kinases, Mgv1 and Gpmk1, production of deoxynivalenol, and expression of genes known to be important for plant infection in F. graminearum were not affected, indicating that the defect of the Δftl1 mutant in plant infection is unrelated to known virulence factors in this pathogen and may involve novel mechanisms. The Δftl1 deletion mutant was significantly reduced in histone deacetylation, and many members of the yeast Set3 complex are conserved in F. graminearum. FTL1 appears to be a component of this well-conserved protein complex that plays a critical role in the penetration and colonization of wheat tissues.The filamentous ascomycete Fusarium graminearum (teleomorph Gibberella zeae) is the main causal agent of Fusarium head blight (FHB), or scab, which is an important disease on wheat and barley throughout the world (18). It also causes stalk and ear rots of maize and infects other small grains. In addition to causing yield losses, this pathogen often contaminates infested grains with trichothecene and estrogenic mycotoxins, such as deoxynivalenol (DON) and zearalenone. Unfortunately, complete resistance to F. graminearum is lacking in wheat, and fungicide application is not cost-effective for FHB control in wheat and barley.F. graminearum overwinters in infected plant debris and produces ascospores in the spring. Ascospores are forcibly discharged from mature perithecia (52) and function as the primary inoculum for FHB. The multicellular conidia or macroconidia are important for spreading the disease in the field and colonizing plant vegetative tissues. Wheat spikes are most susceptible to FHB at anthesis (34a). Although F. graminearum can colonize glumes, anthers are the main site of primary infection on flowering wheat heads (3, 38). Earlier studies indicated that wheat anther extracts stimulate F. graminearum virulence on wheat. Choline and glycine betaine were identified as two major components in anthers that stimulate fungal growth and predispose wheat to F. graminearum infection (50, 51). Under conducive conditions, the fungus can spread from the infected floret along the rachis and cause severe damage. The production of DON, the first virulence factor identified in F. graminearum (11, 42), is not necessary for the initial infection but is important for the spread of FHB on infected wheat heads (2).In the past few years, genetic and genomic studies of F. graminearum have advanced significantly. The genome of F. graminearum has been sequenced (10) and a whole-genome microarray of this haploid homothallic fungus is commercially available (21). A number of pathogenicity or virulence factors have been identified by insertional mutagenesis or targeted gene deletion approaches. Two mitogen-activated protein (MAP) kinase genes, MGV1 and GPMK1, are essential for pathogenicity in F. graminearum (23, 24). Genes that are important for full virulence in F. graminearum on wheat include FGL1 (54), GzCPS1 (31), FBP1 (22), FSR1 (48), SID1 (19), NPS6 (37), RAS2 (5), GzGPA2 and GzGPB1 (56), and HMR1 (47). These virulence-associated genes encode proteins with various biochemical activities, such as lipase, nonribosomal peptide synthase, Ras protein, and 3-hydroxy 3-methylglutaryl coenzyme A reductase. Several genes involved in the primary metabolism, such as the CBL1, RSY1, GzHIS7, ADE5, and ARG2 genes (29, 44, 46) that are required for methionine, histidine, and arginine syntheses, also have been implicated in plant infection in F. graminearum. Overall, molecular mechanisms underlying F. graminearum pathogenesis appear to be complex and remain to be fully understood.In a previous study, we identified 11 restriction enzyme-mediated integration (REMI) mutants that are defective in plant infection (46). In one of these mutants, the transforming vector was inserted in a predicted gene named FTL1 (for Fusarium transducin beta-like gene 1). FTL1 is homologous to the mammalian TBL1 or TBLR1 genes (40, 55) and the Saccharomyces cerevisiae SIF2 gene (8). The products of these genes are components of protein complexes involving histone deacetylases (HDACs). In mammalian cells, TBL1 and TBLR1 are parts of the N-CoR/SMRT/HDAC complexes (40). In yeast, SIF2 is a part of the Set3 complex regulating ascospore formation. In F. graminearum, the Δftl1 gene replacement mutant was significantly reduced in conidiation and failed to cause typical head blight symptoms on flowering wheat heads. It failed to colonize vascular tissues or cause necrosis on the rachis of inoculated wheat heads. The Δftl1 mutant also was defective in spreading from infected anthers to ovaries and was more sensitive than the wild type to plant defensins MsDef1 and osmotin. Although it was normal in the production of deoxynivalenol and the expression of known virulence factors, the Δftl1 mutant was significantly reduced in HDAC activities. FTL1 appears to be a component of this well-conserved HDAC complex that plays a critical role in the penetration and colonization of wheat tissues.     

Hell's Gate globin I: an acid and thermostable bacterial hemoglobin resembling mammalian neuroglobin

Hell's Gate globin I (HGbI), a heme-containing protein structurally homologous to mammalian neuroglobins, has been identified from an acidophilic and thermophilic obligate methanotroph, Methylacidiphilum infernorum. HGbI has very high affinity for O(2) and shows barely detectable autoxidation in the pH range of 5.2-8.6 and temperature range of 25-50°C. Examination of the heme pocket by X-ray crystallography and molecular dynamics showed that conformational movements of Tyr29(B10) and Gln50(E7), as well as structural flexibility of the GH loop and H-helix, may play a role in modulating its ligand binding behavior. Bacterial HGbI's unique resistance to the sort of extreme acidity that would extract heme from any other hemoglobin makes it an ideal candidate for comparative structure-function studies of the expanding globin superfamily.     

Regular dorsal dimples and damaged mites of <Emphasis Type="Italic">Varroa destructor</Emphasis> in some Iranian honey bees (<Emphasis Type="Italic">Apis mellifera</Emphasis>)

The frequency of damaged Varroa destructor Anderson and Trueman (Mesostigmata: Varroidae) found on the bottom board of hives of the honey bee, Apis mellifera L. (Hymenoptera: Apidae) has been used as an indicator of the degree of tolerance or resistance of honey bee colonies against mites. However, it is not clear that this measure is adequate. These injuries should be separated from regular dorsal dimples that have a developmental origin. To investigate damage to Varroa mites and regular dorsal dimples, 32 honey bee (A. mellifera) colonies were selected from four Iranian provinces: Isfahan, Markazi, Qazvin, and Tehran. These colonies were part of the National Honey bee Breeding Program that resulted in province-specific races. In April, Varroa mites were collected from heavily infested colonies and used to infest the 32 experimental colonies. In August, 20 of these colonies were selected (five colonies from each province). Adult bees from these colonies were placed in cages and after introducing mites, damaged mites were collected from each cage every day. The average percentage of injured mites ranged from 0.6 to 3.0% in four provinces. The results did not show any statistical differences between the colonies within provinces for injuries to mites, but there were some differences among province-specific lines. Two kinds of injuries to the mites were observed: injuries to legs and pedipalps, and injuries to other parts of the body. There were also some regular dorsal dimples on dorsal idiosoma of the mites that were placed in categories separate from mites damaged by bees. This type of classification helps identifying damage to mites and comparing them with developmental origin symptoms, and may provide criteria for selecting bees tolerant or resistant to this mite.     

Intracellular production of IFN-alpha 2b in Lactococcus lactis

Human interferon alpha (IFN-α) was expressed in two strains of Lactococcus lactis by aid of two promoters (P32 and Pnis) giving rise to two recombinant strains: MG:IFN and NZ:IFN, respectively. The expression of IFN was confirmed by ELISA and western blotting. Highest production was achieved using glucose for growth of both recombinant strains with nisin, used for induction of the recombinant strain with Pnis promoter, at 30 ng/ml. The optimum time for MG:IFN was 9 h and for NZ:IFN was 4.5 h. The highest productions by MG:IFN and NZ:IFN were 1.9 and 2.4 μg IFN/l, respectively. Both of the expressed IFNs showed bioactivities of 1.9 × 10⁶ IU/mg that were acceptable for further clinical studies.     

Practice and Attitude of Cigarette Smoking: A Community-Based Study

Background

In Saudi Arabia many studies have addressed cigarette smoking from various perspectives. Most of these studies, however, were conducted among males and confined to Riyadh, the capital city. Such limitations have enhanced the need for community-based epidemiological studies that include both genders and various age groups and socio-demographic features, as well as different regions.

Objective

This cross-sectional study aims to assess the prevalence of cigarette smoking and to discuss the association between cigarette smoking habits and socio-demographic factors among community members of the Jazan area in southwest Saudi Arabia.

Methods

A pre-coded questionnaire was designed and tested for data consistency. A well-trained health team was assigned to gather the data from the 30 primary healthcare centers distributed across eight provinces. The response rate was 92.8% (4,326 respondents ≥13 years old). The associations among the subjects'' socio-demographic characteristics were examined by the chi-square test. A multiple logistic regression and odds ratios were calculated as well.

Results

A total of 1,017 (23.5%), 1,042 (24.1%), and 3,284 (75.9%) respondents were, respectively, current smokers (TCS), ever-smokers (TES), and non-smokers (TNS). Though current smokers seem to be more prevalent in urban populations (13.8%) than in rural populations (9.7%), the association of urbanization with a current smoking habit is insignificant.

Conclusion

Having fun, relieving stress, and the influence of parents, particularly of mothers, were the main motives that encouraged participants'' cigarette-smoking habits. This situation was worsened by the fact that accessing cigarettes was either very easy or easy for over 90% of the respondents.     

Microquantification of cholesterol and cholesteryl esters in rat peritoneal macrophages by reverse-phase high-performance liquid chromatography

A simple and rapid method for the microquantification of cholesterol and cholesteryl esters by reverse-phase high performance liquid chromatography has been established. Comparison of elution patterns of authentic cholesterol and cholesteryl esters revealed that a mu Bondasphere reverse-phase C8 (300-A) column was more suitable than a corresponding reverse-phase C4 or C18 column in terms of rapidity and sensitivity. Recovery of cholesterol and cholesteryl esters from a C8 column was greater than 98% when determined either by radioactive cholesterol and cholesteryl oleate or by cholesteryl heptadecanoate. The sensitivity of the quantification ranged from 5 ng to 50 micrograms for both cholesterol and cholesteryl esters. This method was applied to determination of cellular cholesterol and cholesteryl esters of rat peritoneal macrophages. Lipid extracts of these cells were found to contain 38.01 +/- 2.60 micrograms of cholesterol and 3.18 +/- 0.36 micrograms of cholesteryl esters per milligram of cell protein. When the cells were loaded with cholesteryl esters by incubation for 24 h with various concentrations of acetylated low-density lipoprotein, a cellular level of cholesteryl esters showed a dose-dependent increase and reached a maximal level of 106.60 +/- 3.05 micrograms/mg cell protein. Thus, the present method is useful for the microquantification of cholesterol and cholesteryl esters from lipid extracts of biological samples.     

Biochemical characterisation during seed development of oil palm (Elaeis guineensis)

Developmental biochemical information is a vital base for the elucidation of seed physiology and metabolism. However, no data regarding the biochemical profile of oil palm (Elaeis guineensis Jacq.) seed development has been reported thus far. In this study, the biochemical changes in the developing oil palm seed were investigated to study their developmental pattern. The biochemical composition found in the seed differed significantly among the developmental stages. During early seed development, the water, hexose (glucose and fructose), calcium and manganese contents were present in significantly high levels compared to the late developmental stage. Remarkable changes in the biochemical composition were observed at 10 weeks after anthesis (WAA): the dry weight and sucrose content increased significantly, whereas the water content and hexose content declined. The switch from a high to low hexose/sucrose ratio could be used to identify the onset of the maturation phase. At the late stage, dramatic water loss occurred, whereas the content of storage reserves increased progressively. Lauric acid was the most abundant fatty acid found in oil palm seed starting from 10 WAA.