Comparative analysis of sensitivity of cholinesterases of different origin to monoonium reversible inhibitors

The analytic review of the literature data on constants of interaction of cholinesterases of different animal (vertebrates and squids) with 89 onium (ammonium, phosphonium, sulfonium) reversible inhibitors constituting homologous series with regularly varied structure is carried out. Values of the competitive, uncompetitive and generalized inhibitor constants are compared. On the basis of that, conclusions about the mechanism of action of the studied compounds and primary place of their sorption—in “anionic” or peripheral “anionic” sites of enzymes—are made. The presented data are considered from the point of view of comparative biochemistry and in light of current concepts of cholinesterase active center structure.     

Importance of predation by white shrimp Litopenaeus setiferus on estuarine subtidal macrobenthos

Macrobenthic invertebrates are an important food source for higher trophic levels in freshwater and marine habitats, yet the importance of predation impacting regular seasonal changes in macrobenthos abundance remains unclear. Benthic invertebrates and transient marine species in temperate estuaries display inverse patterns of seasonal abundance, suggesting a link between predation and summer macrobenthos abundance minima. We conducted manipulative caging experiments to test the importance of predation by white shrimp (Litopenaeus setiferus) in regulating estuarine subtidal macrobenthos densities. We predicted greater declines in macrobenthos densities with increased shrimp densities due to predation rather than disturbance and macrobenthos emigration. Using these field and laboratory data, we estimate whether white shrimp predation can significantly contribute to the macrobenthos seasonal abundance minima observed in long-term monitoring data.White shrimp predation was measured in the field using 7-d predator enclosure/exclusion experiments. Within the uppermost 0-2 cm of sediment, total macrobenthos densities decreased within shrimp enclosure cages using 12 or 36 shrimp m^− 2. Laboratory experiments distinguished between the effects of shrimp predation versus shrimp disturbance and macrobenthos emigration. Shrimp predation significantly reduced macrobenthos densities, while effects of shrimp disturbance and macrobenthos emigration were not significant in these experiments. Despite the impacts from other ambient predators and other abiotic factors, white shrimp were clearly capable of driving subtidal macrobenthos from their annual maximum density in winter/spring to their summertime minimum density.     

Submergence-induced leaf acclimation in terrestrial species varying in flooding tolerance

Earlier work on the submergence-tolerant species Rumex palustris revealed that leaf anatomical and morphological changes induced by submergence enhance underwater gas exchange considerably. Here, the hypothesis is tested that these plastic responses are typical properties of submergence-tolerant species. Submergence-induced plasticity in leaf mass area (LMA) and leaf, cell wall and cuticle thickness was investigated in nine plant species differing considerably in tolerance to complete submergence. The functionality of the responses for underwater gas exchange was evaluated by recording oxygen partial pressures inside the petioles when plants were submerged. Acclimation to submergence resulted in a decrease in all leaf parameters, including cuticle thickness, in all species irrespective of flooding tolerance. Consequently, internal oxygen partial pressures (pO(2)) increased significantly in all species until values were close to air saturation. Only in nonacclimated leaves in darkness did intolerant species have a significantly lower pO(2) than tolerant species. These results suggest that submergence-induced leaf plasticity, albeit a prerequisite for underwater survival, does not discriminate tolerant from intolerant species. It is hypothesized that these plastic leaf responses may be induced in all species by several signals present during submergence; for example, low LMA may be a response to low photosynthate concentrations and a thin cuticle may be a response to high relative humidity.     

Inbreeding depression in an autotetraploid herb: a three cohort field study

Autotetraploids are predicted to have reduced inbreeding depression relative to diploids. However, recent theory and information on genomic changes following autopolyploidy suggest that inbreeding depression may be closer to diploids. In three consecutive years, self and outcross pollinations were conducted on autotetraploid Campanulastrum americanum, seeds were planted into native sites, and biennial offspring were followed through seed production. Inbred individuals had lower germination rates, reduced survival, were smaller, and flowered later, producing fewer fruits with fewer seeds. Inbred offspring had 6% of the cumulative fitness of outcross offspring. Although performance varied substantially among cohorts, inbreeding depression for cumulative fitness was relatively constant, with delta ranging only from 0.92 to 0.95. C. americanum, like many outcrossing species, expressed very high amounts of inbreeding depression. This supports the hypothesis that inbreeding depression of some autotetraploids may be similar to that of diploids. Furthermore, few studies have measured temporal variation in inbreeding depression. Constant inbreeding depression given a sixfold range in cohort performance suggests that inbreeding depression may be relatively robust to environmental variation experienced by natural populations.     

Nona-coordinated MO6N3 centers M = Zr, Hf as a stable building block for the construction of heterometallic alkoxide precursors

The modification of zirconium or hafnium alkoxides with diethanolamine, H₂dea, leads to the formation of unique nona-coordinated M{μ-η³-NH(C₂H₄O)₂}₃ cores. The mechanism is used to develop a self-assembly approach to the first thermodynamically stable zirconium-titanium and hafnium-titanium precursors, Zr{μ-η³-NH(C₂H₄O)₂}₃[Ti(OⁱPr)₃]₂ (1) and Hf{μ-η³-NH(C₂H₄O)₂}₃[Ti(OⁱPr)₃]₂ (2). Mass spectrometric characterization of these compounds demonstrates their volatility. In addition to the solution stability of these compounds the volatility makes them attractive single source precursors for MOCVD and ALD applications. These precursors are also interesting candidates for application in sol-gel synthesis of microporous materials as the stability of the core prevents self-assembly of ligands on the outer surface of the primary particles formed during the hydrolysis. A n-propoxide analog of 1 can be prepared from zirconium n-propoxide but does not yield any crystalline material. It is demonstrated that 1 can be prepared from [Zr(OⁿPr)(OⁱPr)₃(ⁱPrOH)]₂, however, with a lower yield compared to the use of zirconium isopropoxide. The single crystals obtained from systems containing zirconium isopropoxide, titanium isopropoxide and triethanolamine H₃tea turned out to be Ti₂(OⁱPr)₂({μ-η⁴-NH(C₂H₄O)₃}₂)₂ (4). Theoretical calculations indicate that the octacoordinate M{μ-η⁴-N(C₂H₄O)₃}₂ core, anticipated in reaction with H₃tea, will have metal-nitrogen bonds that are too long for its stabilization. This explains why the formation of 4 is thermodynamically favored over the formation of heterometallic species.     

A comparative analysis of the temperature response of leaf elongation in Bromus stamineus and Lolium perenne plants in the field: intrinsic and size-mediated effects

BACKGROUND AND AIMS: Growth of grass species in temperate-humid regions is restricted by low temperatures. This study analyses the origin (intrinsic or size-mediated) and mechanisms (activity of individual meristems vs. number of active meristems) of differences between Bromus stamineus and Lolium perenne in the response of leaf elongation to moderately low temperatures. METHODS: Field experiments were conducted at Balcarce, Argentina over 2 years (2003 and 2004) using four cultivars, two of B. stamineus and two of L. perenne. Leaf elongation rate (LER) per tiller and of each growing leaf, number of growing leaves and total leaf length per tiller were measured on 15-20 tillers per cultivar, for 12 (2003) or 10 weeks (2004) during autumn and winter. KEY RESULTS: LER was faster in B. stamineus than in L. perenne. In part, this was related to size-mediated effects, as total leaf length per tiller correlated with LER and B. stamineus tillers were 71% larger than L. perenne tillers. However, accounting for size effects revealed intrinsic differences between species in their temperature response. These were based on the number of leaf meristems simultaneously active and not on the (maximum) rate at which individual leaves elongated. Species differences were greater at higher temperatures, being barely notable below 5 degrees C (air temperature). CONCLUSIONS: Bromus stamineus can sustain a higher LER per tiller than L. perenne at air temperatures > 6 degrees C. In the field, this effect would be compounded with time as higher elongation rates lead to greater tiller sizes.     

Common variation in KLKB1 and essential hypertension risk: tagging-SNP haplotype analysis in a case-control study

The human plasma kallikrein gene (KLKB1) encodes plasma kallikrein, a serine protease that catalyzes the release of kinins and other vasoactive peptides and may be involved in the pathogenesis of hypertension. In this study, we performed a haplotype-based study to assess the effect of common genetic variation in the KLKB1 gene on the risk of essential hypertension. Eight common single nucleotide polymorphisms (SNPs) were selected from the HapMap database and used to determine the pattern of linkage disequilibrium (LD) and haplotype structure within the KLKB1 gene. Four tag SNPs were then identified with over 85% power to predict both common haplotypes and remaining common SNPs, and genotyped in 1,317 cases with essential hypertension and 1,269 healthy controls. Single SNP analyses indicated that SNPs rs2304595 and rs4253325 were significantly associated with hypertension, adjusted for covariates. Compared with the most common Hap2 CAGC, Hap1 AGAC and Hap3 CGAC, which carry the susceptible rs2304595 G allele and rs4253325 A allele, were found to significantly increase the risk of essential hypertension with adjusted odds ratios equal to 1.37 and 1.17, respectively (P < 0.0001 and 0.028). A strongly significant interaction with gene-drinking was also observed. Among drinkers, the adjusted OR for Hap1 relative to Hap2 was increased to 2.50 (95% CI, 2.40 to 2.61; P < 0.0001). This was the first study to perform association analysis of the KLKB1 gene with essential hypertension. Our findings suggested that common genetic variation in the KLKB1 gene might contribute to the risk of hypertension in the northern Han Chinese population. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Conflict of interests: None.     

Fas Antigen and Sporadic Alzheimer’s Disease in Southern Italy: Evaluation of Two Polymorphisms in the TNFRSF6 Gene

Tumor Necrosis Factor Receptor Super Family 6 gene (TNFRSF6), also known as FAS, encodes the Fas antigen, a cell surface receptor mediating cell apoptosis, situated on chromosome 10q located near the region of linkage to sporadic Alzheimer’s disease (sAD). FAS levels have been reported elevated in the brain of AD patients. Due to both positional and pathobiological criteria, the association of the FAS antigen with this pathology is of great interest. We have tested two SNPs in the FAS gene in 223 Italian patients with non-familial AD from Southern Italy (Calabria region) and 211 healthy control subjects. No significant differences in allelic and genotypic distributions were found between cases and controls, or late and early-onset AD patients, thus suggesting that these polymorphisms do not represent an AD risk factor in our population.     

中药贝母的基原植物和药用亲缘学的研究

贝母是一种常用中药,有十分悠久的药用历史。百合科Liliaceae中的贝母属Fritillaria是中药贝母的主要来源,此属全世界约有130种,我国由于近年来发表了大量的新种和新变种,使国产贝母属的种名达到80个,变种名称52个,变型名称6个。大量新分类名称的出现对中药贝母的质量控制和应用方面造成一定困难。通过对中药贝母的历史沿革、植物分类、地理分布、化学成分、现今生产及应用等的综合研究整理,将中药贝母划分为6个类型:浙贝母、川贝母、伊贝母、湖北贝母、平贝母和安徽贝母。这样的划分除安徽贝母尚未收载于药典外,其他均与现行版的中华人民共和国药典(2005版)一部所收载的内容一致。通过此项研究,作者建议,凡是主要经济植物的新名称的出现必须更加慎重,而且从实际应用的观点出发,分类群的划分不宜过细。     

Mycobacterium species identification--a new approach via dnaJ gene sequencing

The availability of the dnaJ1 gene for identifying Mycobacterium species was examined by analyzing the complete dnaJ1 sequences (approximately 1200 bp) of 56 species (54 of them were type strains) and comparing sequence homologies with those of the 16S rRNA gene and other housekeeping genes (rpoB, hsp65). Among the 56 Mycobacterium species, the mean sequence similarity of the dnaJ1 gene (80.4%) was significantly less than that of the 16S rRNA, rpoB and hsp65 genes (96.6%, 91.3% and 91.1%, respectively), indicating a high discriminatory power of the dnaJ1 gene. Seventy-one clinical isolates were correctly clustered to the corresponding type strains, showing isolates belonging to the same species. In order to propose a method for strain identification, we identified an area with a high degree of polymorphism, bordered by conserved sequences, that can be used as universal primers for PCR amplification and sequencing. The sequence of this fragment (approximately 350 bp) allows accurate species identification and may be used as a new tool for the identification of Mycobacterium species.