Dispersal ability rather than ecological tolerance drives differences in range size between lentic and lotic water beetles (Coleoptera: Hydrophilidae)

Aim In aquatic ecosystems, standing (lentic) and running (lotic) waters differ fundamentally in their stability and persistence, shaping the comparative population genetic structure, geographical range size and speciation rates of lentic versus lotic lineages. While the drivers of this pattern remain incompletely understood, the suite of traits making up the ability of a species to establish new populations is instrumental in determining such differences. Here we explore the degree to which the association between habitat type and geographical range size results from differences in dispersal ability or fundamental niche breadth in the members of the Enochrus bicolor complex, an aquatic beetle clade with species across the lentic–lotic divide. Location Western Mediterranean, with a special focus on North Africa, the Iberian Peninsula and Sicily. Methods DNA sequences for four loci were obtained from species of the E. bicolor complex and analysed using phylogenetic inference. Dispersal and establishment abilities were assessed in lentic–lotic species pairs of the complex, using flight wing morphometrics and thermal tolerance ranges as surrogates, respectively. Results There were clear differences in range size between the lotic and lentic taxa of the complex, which appears to have had a lotic origin with two transitions to standing waters. Only small differences were observed in temperature tolerance and acclimation ability between the two lotic–lentic sister species studied. By contrast, wing morphometrics revealed clear, consistent differences between lotic and lentic Enochrus species pairs, the latter having a higher dispersal capacity. Main conclusions We hypothesize that there have been two habitat shifts from lotic to lentic waters, which have allowed marked expansions in geographical range size in western Mediterranean species of the E. bicolor complex. Differences in dispersal rather than in establishment ability appear to underlie differences in geographical range extent, as transitions to lentic waters were associated with changes in wing morphology, but not in thermal tolerance range. In this lineage of water beetles, selection for dispersal in geologically short‐lived lentic systems has driven the evolution of larger range sizes in lentic taxa compared with those of their lotic relatives.     

The Pseudomonas aeruginosa Mannose Sensitive Hamemagglutination Strain (PA-MSHA) Induces a Th1-Polarizing Phenotype by Promoting Human Dendritic Cells Maturation

Pseudomonas aeruginosa mannose sensitive hamemagglutination strain (PA-MSHA) is a kind of peritrichous P. aeruginosa strain with MSHA fimbriae and has been shown to activate kinds of immunocytes. Dendritic cells (DCs) are specialized antigen-presenting cells required for the stimulating and priming CD4⁺ T cells toward the T helper cell type 1 (Th1), Th2 and other different phenotypes. PA-MSHA effecting on Th1 remains an important missing link. Here we demonstrated that PA-MSHA augmented monocytes derived-dendritic cells (Mo-DCs) expression of HLA-DR, co-stimulatory and adhesion molecules, and induced Th1-promoting interleukin-12 and tumor necrosis factor α secretion, in addition, PA-MSHA treated Mo-DCs displayed lesser endocytic capacity. Furthermore, in mixed lymphocyte reactions, allostimulatory capacity of Mo-DCs was enhanced by PA-MSHA, CD4⁺ T cells stimulated by PA-MSHA -activated Mo-DCs showed a Th1-polarized cytokine production, increasing secretion of IFN-γ and decreasing secretion of IL-10 and IL-4. Our findings identified PA-MSHA as an important exogenous factor that induced DCs maturation toward a Th1-promoting phenotype.     

Myocardial protection by Protykin,a novel extract of trans-resveratrol and emodin

Protykin is an all-natural, high potency standardized extract of trans-resveratrol (20%) and emodin (10%) derived from the dried rhizome of Polygonum cuspidatum. Previous studies have demonstrated free radical scavenging and anti-inflammatory activities of resveratrol. Since free radicals play a crucial role in the pathogenesis of myocardial ischemia/reperfusion injury, we examined whether Protykin could preserve the heart during ischemic arrest. Sprague—Dawley rats were divided into two groups: experimental group was gavaged Protykin (100 mg/kg body wt) dissolved in corn oil for three weeks, while the control group was gavaged corn oil alone. After three weeks, rats were sacrificed, isolated hearts perfused via working mode, were made globally ischemic for 30 min followed by 2 h of reperfusion. Left ventricular functions were continuously monitored and malonaldehyde (MDA) (presumptive marker for oxidative stress) formation were estimated. At the end of each experiment, myocardial infarct size was measured by TTC staining method. Peroxyl radical scavenging activity of Protykin was determined by examining its ability to remove peroxyl radical generated by 2,2′-azobis (2-amidinopropane) dihydrochloride, while hydroxy radical scavenging activity was tested with its ability to reduce 7-OH^·-coumarin-3-carboxylic acid. The results of our study demonstrated that the Protykin group provided cardioprotection as evidenced by improved post-ischemic left ventricular functions (dp, dp/dt_max) and aortic flow as compared to control group. This was further supported by the reduced infarct size in the Protykin group. Formation of MDA was also reduced by Protykin treatment. In vitro studies demonstrated that Protykin possessed potent peroxyl and hydroxyl radical scavenging activities. The results of this study indicate that Protykin can provide cardioprotection, presumably by virtue of its potent free radical scavenging activity.     

Generation of hydrogen peroxide,superoxide anion and the hydroxyl free radical from polyphenols and active benzene metabolites: Their possible role in mutagenesis

Benzene is strongly suspected of being an animal and human carcinogen, but the mechanisms by which it induces tumors of lymphoid and hematopoietic organs are unknown. Production of active oxygen species from benzene metabolites [hydroquinone (HQ), catechol and 1,2,4-benzenetriol (1,2,4-BT) and related polyphenols (resorcinol, pyrogallol and phloroglucinol) are investigated. Pyrogallol and 1,2,4-BT can produce H₂O₂, O ₂ ^– and^·OH simultaneously, and have powerful mutagenic potential. Resorcinol and phloroglucinol cannot produce all of the active oxygen species, and show no mutagenic effects. Catechol can produce H₂O₂, but cannot produce O ₂ ^– and^·OH, and has no mutagenic activity. These data strongly support the hypothesis that benzene metabolites can cause mutagenicity via the generation of oxygen radicals. Although HQ produces H₂O₂ only, and less than produced by pyrogallol and 1,2,4-BT, the mutagenicity of HQ is higher. The results indicate that HQ may act via another mechanism to cause mutagenicity. In the presence of trace metal ions, the reactivity of polyphenols is increased. The biological significance of these phenomena are investigated and discussed.     

退化柞蚕林封育对枯落物和表层土壤持水效能的影响

柞蚕林是辽东山区退化最严重的森林类型之一,因多年反复刈割导致生长逐渐衰退、更新能力下降,局部出现空地甚至土壤开始砂化,涵养水源和保持水土等生态功能明显降低。以辽东山区的退化柞蚕林为研究对象,分析了在封育9、12、21a后森林的枯落物及表层土壤持水效能。结果表明:退化柞蚕林经过封育恢复后,封育恢复时间越长,林地枯落物累积量增加的越显著,枯落物持水能力和有效拦蓄降雨能力提高也越明显。对照(未封育)、封育9、12、21a柞蚕林枯落物储量分别为3.69、7.92、8.41 t/hm~2和8.74 t/hm~2;最大持水量分别为6.23、14.71、15.81 t/hm~2和17.18 t/hm~2,有效拦蓄量分别为4.78、10.87、11.70、12.78 t/hm~2。枯落物持水量与浸水时间存在显著的相关关系(P0.001),自然对数模型模拟拟合效果最好(R~20.9)。退化柞蚕林经过封育恢复后,表层土壤水文物理性质的改善随着封育恢复时间的增加而越来越明显,封育9、12和21年柞蚕林表层土壤容重分别比对照退化柞蚕林降低了5.51%、12.60%、17.32%,毛管持水量分别增加了7.01%、28.98%、54.83%,非毛管持水量分别增加了46.14%、126.19%、187.19%。本研究结果说明退化柞蚕林封育能够通过提高其林地枯落物和改善土壤物理性质,增加表层土壤持水效能,对恢复和改善退化柞蚕林地的生态环境、恢复森林生产力具有重要作用。     

Antioxidant activity of fractionated extracts of rhizomes of high-altitude Podophyllum hexandrum: Role in radiation protection

Whole extract of rhizomes of Podophyllum hexandrum has been reported earlier by our group to render whole-body radioprotection. High-altitude P. hexandrum (HAPH) was therefore fractionated using solvents of varying polarity (non-polar to polar) and the different fractions were designated as, n-hexane (HE), chloroform (CE), alcohol (AE), hydro-alcohol (HA) and water (WE). The total polyphenolic content (mg% of quercetin) was determined spectrophotometrically, while. The major constituents present in each fraction were identified and characterized using LC-APCI/MS/MS. In vitro screening of the individual fractions, rich in polyphenols and lignans, revealed several bioactivities of direct relevance to radioprotection e.g. metal-chelation activity, antioxidant activity, DNA protection, inhibition of radiation (250 Gy) and iron/ascorbate-induced lipid peroxidation (LPO). CE exhibited maximum protection to plasmid (pBR322) DNA in the plasmid relaxation assay (68.09% of SC form retention). It also showed maximal metal chelation activity (41.59%), evaluated using 2,2-bipyridyl assay, followed by AE (31.25%), which exhibited maximum antioxidant potential (lowest absorption unit value: 0.0389± 0.00717) in the reducing power assay. AE also maximally inhibited iron/ascorbate-induced and radiation-induced LPO (99.76 and 92.249%, respectively, at 2000 g/ml) in mouse liver homogenate. Under conditions of combined stress (radiation (250 Gy) + iron/ascorbate), at a concentration of 2000 g/ml, HA exhibited higher percentage of inhibition (93.05%) of LPO activity. HA was found to be effective in significantly (p < 0.05) lowering LPO activity over a wide range of concentrations as compared to AE. The present comparative study indicated that alcoholic (AE) and hydro-alcoholic (HA) fractions are the most promising fractions, which can effectively tackle radiation-induced oxidative stress.     

Understorey vegetation moderates climate in open forests: The role of the skirt-forming grass tree Xanthorrhoea semiplana F.Muell

Microsites are created by abiotic and biotic features of the landscape and may provide essential habitats for the persistence of biota. Forest canopies and understorey plants may moderate wind and solar radiation to create microclimatic conditions that differ considerably from regional climates. Skirt-forming plants, where senescent leaves create hut-like cavities around the stem, create microsites that are sheltered from ambient conditions and extreme weather events, constituting potential refuges for wildlife. We investigate day and night temperatures and humidity for four locations (grass tree cavities, soil, 20 cm above-ground, 1 m above-ground) in a South Australian forest with relatively open canopy of stringybark eucalypts (Eucalyptus baxteri, E. obliqua) and an understorey of skirt-forming grass trees (Xanthorrhoea semiplana) at 5, 10, 20, and 40 m from the forest edge. We also measured the percentage of canopy and understorey covers. Generally, temperature and humidity differed significantly between more sheltered (grass tree cavities, soil) and open-air microsites, with the former being cooler during the day and warmer and more humid during the night. Furthermore, our results suggest that canopy cover tends to decrease, and understorey cover tends to increase, the temperature of microsites. Distance to the edge was not significantly related to temperature for any microsite, suggesting that the edge effect did not extend beyond 10 m from the edge. Overall, grass trees influenced microclimatic conditions by forming a dense understorey and providing cavities that are relatively insulated. The capacity of grass tree cavities to buffer external conditions increased linearly with ambient temperatures, by 0.46°C per degree increase in maximum and 0.25°C per degree decrease in minimum temperatures, potentially offsetting climate warming and enabling persistence of fauna within their thermal limits. These climate moderation properties will make grass trees increasingly important refuges as extreme weather events become more common under anthropogenic climate change.     

Protein-mediated hydroxyl radical generation--the primary event in NADH oxidation and oxygen reduction by the granule rich fraction of human resting leukocytes.

The granule rich-fraction isolated from human resting polymorphonuclear leukocytes is capable of CN-insensitive NADH oxidation and O₂-uptake, accompanied by production of superoxide anion, hydroxyl radicals and H₂O₂. We showed that H₂O₂ initiates and maintains NADH oxidation and O₂-uptake but is also necessary for the formation of superoxide anion and hydroxyl radicals. It acts as a primary substrate for CN-insensitive protein-mediated formation of hydroxyl radicals, which in turn produce superoxide anions, probably through univalent oxidation of NADH as an intermediary.     

Diagnostic utility of HFE variants in Spanish patients: Association with HLA alleles and role in susceptibility to acute lymphoblastic leukemia

Two single nucleotide polymorphisms (SNPs) in the Human Hemochromatosis (HFE) gene, C282Y and H63D, are the major variants associated to altered iron status and it is well known that these mutations are in linkage disequilibrium with certain Human Leukocyte Antigen (HLA)-A alleles. In addition, the C282Y SNP has been previously suggested to confer susceptibility to acute lymphoblastic leukemia (ALL). We have aimed to assess the diagnosis utility of these polymorphisms in a population of Spanish subjects with suspicion of hereditary iron overload and to evaluate the effect of their associations with HLA-A alleles on the susceptibility to ALL. Both the 63DD [OR = 4.31 (1.7–11.2)] and 282YY (p for trend = 0.02) genotypes were more frequently found among subjects with suspicion of iron overload than among controls. 282YY carriers displayed significantly higher transferrin saturation index (TSI) values (p < 0.001) as well as serum iron (p = 0.01) and ferritin (p = 0.01) levels. In addition, transferrin levels were lower in these subjects (p = 0.01). Likewise, patients who were carriers of the compound heterozygous diplotype (282CY/63HD) showed significantly higher TSI and serum iron and ferritin concentrations. The H63D SNP did not significantly affect the analytical parameters measured. All 282YY carriers and 69.2% of compound heterozygotes showed an altered biochemical index. The frequencies of the HFE SNPs in ALL pediatric patients were lower than those found in controls, whereas the HLA-A*24 allele was significantly overrepresented in the patients group [OR = 3.76 (1.9–7.3)]. No HFE-HLA-A associations were found to modulate the ALL risk. These results suggest that it may be useful to test for both HFE H63D and C282Y polymorphisms in patients with iron overload, as opposed to just genotyping for the C282Y SNP, which is customary in some healthcare centers. These HFE variants and their associations with HLA-A alleles were not observed to be relevant for the susceptibility to ALL in our population.