Spatial partitioning and asymmetric hybridization among sympatric coastal steelhead trout (Oncorhynchus mykiss irideus), coastal cutthroat trout (O. clarki clarki) and interspecific hybrids

Hybridization between sympatric species provides unique opportunities to examine the contrast between mechanisms that promote hybridization and maintain species integrity. We surveyed hybridization between sympatric coastal steelhead (Oncorhynchus mykiss irideus) and coastal cutthroat trout (O. clarki clarki) from two streams in Washington State, Olsen Creek (256 individuals sampled) and Jansen Creek (431 individuals sampled), over a 3-year period. We applied 11 O. mykiss-specific nuclear markers, 11 O. c. clarki-specific nuclear markers and a mitochondrial DNA marker to assess spatial partitioning among species and hybrids and determine the directionality of hybridization. F1 and post-F1 hybrids, respectively, composed an average of 1.2% and 33.6% of the population sampled in Jansen Creek, and 5.9% and 30.4% of the population sampled in Olsen Creek. A modest level of habitat partitioning among species and hybrids was detected. Mitochondrial DNA analysis indicated that all F1 hybrids (15 from Olsen Creek and five from Jansen Creek) arose from matings between steelhead females and cutthroat males implicating a sneak spawning behaviour by cutthroat males. First-generation cutthroat backcrosses contained O. c. clarki mtDNA more often than expected suggesting natural selection against F1 hybrids. More hybrids were backcrossed toward cutthroat than steelhead and our results indicate recurrent hybridization within these creeks. Age analysis demonstrated that hybrids were between 1 and 4 years old. These results suggest that within sympatric salmonid hybrid zones, exogenous processes (environmentally dependent factors) help to maintain the distinction between parental types through reduced fitness of hybrids within parental environments while divergent natural selection promotes parental types through distinct adaptive advantages of parental phenotypes.     

Air quality biomonitoring in agricultural areas nearby to urban and industrial emission sources in Córdoba province,Argentina, employing the bioindicator Tillandsia capillaris

The air quality in agricultural areas close to industrial emission sources (chemical, metallurgical and cement plant) was evaluated through a biomonitoring study employing the epiphytic species Tillandsia capillaris Ruíz and Pav. f. capillaris. Plants were collected from a non-contaminated area in the province of Córdoba (reference site) and transplanted back to this site and into three industrial areas representing different emission sources of air pollutants: cement plant, chemical and metallurgical industries. Biomonitors were exposed to ambient air for four periods of 3 months each during one year (for determination of physiological parameters) and for four periods of 6 months each during two years (for determination of trace elements). In the exposure period coinciding with the winter season (i.e., the dry season) the plants showed the strongest global physiological damage, possibly due to higher air pollutant concentrations. The comparison among study areas indicates the highest values of foliar damage index at the chemical industries sites, possibly due to the emission of oxidizing pollutants. On the other hand, heavy metals and trace element concentrations (V, Fe, Co, Cu, Br, Ni, Zn and Pb) were associated mainly with metallurgical industries, although the chemical industries and the cement plant were associated with Ni, Zn and Ca accumulation in the biomonitor, respectively. Considering that these sites with high industrial activity are located close to soybean producing areas, further environmental and toxicological studies are necessary, taking into account food safety and human health.     

Amplification ratio control system for copy number variation genotyping

We describe a generic design for ratiometric analysis suitable for determination of copy number variation (CNV) class of a gene. Following two initial sequence-specific PCR priming cycles, both ends of both amplicons (one test and one reference) in a duplex reaction, are all primed by the same universal primer (UP). Following each amplification denaturation step, the UP target and its reverse complement (UP') in each strand form a hairpin. The bases immediately beyond the 3'-end of the UP and 5' of UP' are chosen such as not to base pair in the hairpin (otherwise priming is ablated). This hairpin creates a single constant environment for priming events and chaperones free 3'-ends of amplicon strands. The resultant 'amplification ratio control system' (ARCS) permits ratiometric representation of amplicons relative to the original template into PCR plateau phase. These advantages circumvent the need for real-time PCR for quantitation. Choice of different %(G+C) content for the target and reference amplicons allows liquid phase thermal melt discrimination and quantitation of amplicons. The design is generic, simple to set up and economical. Comparisons with real-time PCR and other techniques are made and CNV assays demonstrated for haptoglobin duplicon and 'chemokine (C-C motif) ligand 3-like 1' gene.     

Decreased Electroconvulsive Shock-Induced Diacylglycerols and Free Fatty Acid Accumulation in the Rat Brain by Ginkgo biloba Extract (EGb 761): Selective Effect in Hippocampus as Compared with Cerebral Cortex

Abstract: The effect of Ginkgo biloba extract (EGb 761) treatment (100 mg/kg/day, per os, for 14 days) on electroconvulsive shock (ECS)-induced accumulation of free fatty acids (FFA) and diacylglycerols (DAG) was analyzed in rat cerebral cortex and hippocampus. EGb 761 reduced the FFA pool size by 33% and increased the DAG pool by 36% in the hippocampus. These endogenous lipids were unaffected in cerebral cortex. During the tonic seizure (10 s after ECS) the fast accumulation of FFA, mainly 20:4, was similar in sham- and EGb 761 -treated rats, in both the cerebral cortex and hippocampus. However, further accumulation of free 18:0 and 20:4, observed in the hippocampus of sham-treated rats during clonic seizures (30 s to 2 min after ECS), did not occur in EGb 761-treated animals. The rise in DAG content triggered in the cortex and hippocampus by ECS was delayed by EGb 761 treatment from 10 s to 1 min, when values similar to those in sham animals were attained. Moreover, in the hippocampus the size of the total DAG pool was decreased by 19% during the tonic seizure. At later times, DAG content showed a faster decrease in EGb 761-treated rats. By 2 min levels of all DAG acyl groups decreased to values significantly lower than in sham animals in both cortex and hippocampus. This study shows that EGb 761 treatment affects, with high selectivity, lipid metabolism and lipid-derived second messenger release and removal in the hippocampus, while affecting to a lesser extent the cerebral cortex.     

Nanovesicles Are Secreted during Pollen Germination and Pollen Tube Growth： A Possible Role in Fertilization

Dear Editor, During recent decades, a novel mechanism of secretion has been identified in a wide range of mammalian cells. It involves the release of bioactive membrane nanovesicles （30-100 nm）, termed exosomes, upon the fusion of multivesicular bodies with the plasma membrane （Thery et al., 2009）. Exosomes are implicated in diverse functions, such as scavenging of archaic proteins, intercellular messengers delivering cell-specific signals, and vehicles for transmissible pathogens. Exosomes have also been described in other organisms such as bacte- ria, Drosophila, and fungi.     

Fatty acyl-AMP as an intermediate in fatty acid reduction to aldehyde in luminescent bacteria

The acyl protein synthetase component (50K) of the fatty acid reductase complex from the luminescent system of Photobacterium phosphoreum has been found to catalyze the activation of fatty acid via formation of an enzyme bound acyl-AMP (carboxyphosphate mixed anhydride) immediately prior to the acylation of the enzyme. PPi-ATP exchange and nucleotide binding experiments are dependent on fatty acid and indicate that the fatty acyl-AMP is directly formed and that an adenylated enzyme intermediate is not part of the mechanism. The formation of acyl-AMP from fatty acid and ATP is reversible with a standard free energy of -2 kcal/mol, and is dependent on Mg2+. The fatty acyl-AMP intermediate has been isolated and shown to be part of the pathway of fatty acid reduction. The 34K component of the complex, which strongly stimulates the acylation of the 50K protein by fatty acyl-AMP or fatty acid and ATP, is not required for the formation of acyl-AMP showing that it differentially affects the fatty acid activation and acylation steps catalyzed by the 50K protein.     

Sterculic acid antagonizes 7-ketocholesterol-mediated inflammation and inhibits choroidal neovascularization

Sterculic acid is a cyclopropene fatty acid with numerous biological activities. In this study we demonstrate that sterculic acid is a potent inhibitor of endoplasmic reticulum (ER) stress and related inflammation caused by 7-ketocholesterol (7KCh). 7KCh is a highly toxic oxysterol suspected in the pathogenesis of various age-related diseases such as atherosclerosis, Alzheimer's disease and age-related macular degeneration. Sterculic acid demonstrated to be 5-10 times more effective than other anti-inflammatory fatty acids at inhibiting 7KCh-mediated inflammatory responses in cultured cells. In vivo, sterculic acid was effective at inhibiting the formation of choroidal neovascularization (CNV) in the laser-injury rat model. Our data suggests that sterculic acid may be useful in treating CNV in certain forms of age-related macular degeneration.     

A genetic map of tetraploid <Emphasis Type="Italic">Paspalum notatum</Emphasis> Flügge (bahiagrass) based on single-dose molecular markers

Paspalum notatum Flügge is a warm-season forage grass with mainly diploid (2n = 20) and autotetraploid (2n = 40) representatives. Diploid races reproduce sexually and require crosspollination due to a self-incompatible mating system, while autotetraploids reproduce by aposporous apomixis. The objectives of this work were to develop a genetic linkage map of Paspalum notatum Flügge at the tetraploid level, identify the linkage/s group/s associated with apomixis and carry out a general characterization of its mode of inheritance. A pseudo test-cross F₁ family of 113 individuals segregating for the mode of reproduction was obtained by crossing a synthetic completely sexual tetraploid plant (Q4188) as female parent with a natural aposporous individual (Q4117) as pollen donor. Map construction was based on single-dose markers (SDAFs) segregating from both parents. Two linkage maps (female and male) were constructed. Within each map, homologous groups were assembled by detecting repulsion-phase linked SDAFs. Putative Q4188 and Q4117 homolog groups were identified by mapping shared single dose markers (BSDF). The Q4188 map consisted of 263 markers distributed on 26 co-segregation groups over a total genetic distance of 1.590.6 cM, while the Q4117 map contained 216 loci dispersed on 39 co-segregation groups along 2.265.7 cM, giving an estimated genome coverage of 88% and 83%, respectively. Seven and 12 putative homologous chromosomes were detected within Q4188 and Q4117 maps, respectively. Afterward, ten female and male homologous chromosomes were identified by mapping BSDFs. In the Q4117 map, a single linkage group was associated with apospory. It was characterized by restriction in recombination and preferential chromosome pairing. A BPSD marker mapping within this group allowed the detection of the female homolog and the putative four male groups of the set carrying apospory.     

Structural and physiological features of sterols necessary to satisfy bulk membrane and sparking requirements in yeast sterol auxotrophs

A variety of sterols and stanols have been analyzed for their ability to satisfy bulk membrane and high-specificity (sparking) functions in three yeast sterol auxotrophs. While many sterols and stanols satisfied bulk membrane requirements, only those possessing a C-5,6 unsaturation or capable of being desaturated at C-5 fulfilled the high-specificity sparking requirement. Unsaturation of the A-ring or beta-saturation of a C-5,6 double bond rendered both sterol and stanol unsuitable for either function. The C-28 methyl group of ergosterol, while not required for growth, allowed for greater ease of desaturation at C-5 in vivo. As a result some sterols and stanols lacking the C-28 methyl were incapable of satisfying the sparking requirement while identical compounds possessing the C-28 methyl were able to fulfill the sparking function(s). These data are extended to hypothesize a role for the C-28 methyl group of ergosterol in yeast.