When sexual meets apomict: genome size,ploidy level and reproductive mode variation of Sorbus aria s.l. and S. austriaca (Rosaceae) in Bosnia and Herzegovina

Background and Aims Allopolyploidy and intraspecific heteroploid crosses are associated, in certain groups, with changes in the mating system. The genus Sorbus represents an appropriate model to study the relationships between ploidy and reproductive mode variations. Diploid S. aria and tetraploid apomictic S. austriaca were screened for ploidy and mating system variations within pure and sympatric populations in order to gain insights into their putative causalities.Methods Flow cytometry was used to assess genome size and ploidy level among 380 S. aria s.l. and S. austriaca individuals from Bosnia and Herzegovina, with 303 single-seed flow cytometric seed screenings being performed to identify their mating system. Pollen viability and seed set were also determined.Key Results Flow cytometry confirmed the presence of di-, tri- and tetraploid cytotype mixtures in mixed-ploidy populations of S. aria and S. austriaca. No ploidy variation was detected in single-species populations. Diploid S. aria mother plants always produced sexually originated seeds, whereas tetraploid S. austriaca as well as triploid S. aria were obligate apomicts. Tetraploid S. aria preserved sexuality in a low portion of plants. A tendency towards a balanced 2m : 1p parental genome contribution to the endosperm was shared by diploids and tetraploids, regardless of their sexual or asexual origin. In contrast, most triploids apparently tolerated endosperm imbalance.Conclusions Coexistence of apomictic tetraploids and sexual diploids drives the production of novel polyploid cytotypes with predominantly apomictic reproductive modes. The data suggest that processes governing cytotype diversity and mating system variation in Sorbus from Bosnia and Herzegovina are probably parallel to those in other diversity hotspots of this genus. The results represent a solid contribution to knowledge of the reproduction of Sorbus and will inform future investigations of the molecular and genetic mechanisms involved in triggering and regulating cytotype diversity and alteration of reproductive modes.     

Chromosome differentiation of four 2n = 50 chromosomal forms of Turkish mole rat, Nannospalax nehringi

Nannospalax is a genus of blind rodents adapted to living in underground. The species have numerous chromosomal forms in Turkey, and their taxonomic position is still unknown. In this study, 15 mole rats of four different 2n = 50 forms were used; C- and G- banding processes were applied; and a comparison was made accordingly. Karyological results showed that the 2n = 50S form is a new form for Turkish blind mole rats. 2n = 50S form is determined from Andirin (Kahramanmara?) and has NF = 70. The 2n = 50W form, on the other hand, differs from the others with NF = 74 form. C-banding results showed that heterochromatin blocks of all 2n = 50 are different, while only the 2n = 50W form has telomeric heterochromatin blocks. G-banding results, however, displayed homologies and differences among the chromosomal forms. After comparison, we determined that Robertsonian fusion is an efficient force on chromosomal evolution in blind mole rats in Turkey, and that telomeric heterochromatin is a distinctive character for the 2n = 50W form. We suggest that the chromosomal changing mechanism should be independent from climatic peculiarities. These results support the theory that ancestral karyotype should have the largest distribution in a chromosomally variable species.     

Artificial neural networks (ANN) approach for modeling of removal of Lanaset Red G on Chara contraria

A three-layer artificial neural network (ANN) was constructed to predict the removal efficiency of Lanaset Red (LR) G on Chara contraria based on 2304 experimental sets. The effects of operating variables (particle size, adsorbent dosage, pH regimes, dye concentration, and contact time) were studied to optimize the sorption conditions of this dye. The operating variables were used as the input to the constructed neural network to predict the dye uptake at any time as the output. This adsorbent was characterized by FTIR. Pseudo second-order model was also fitted to the experimental data. According to values of error analyses and determinations coefficient, the ANN was more appropriate to describe this adsorption process. Result of this model indicated that pH regimes had the highest importance effect (49%) on the dye uptake.     

Cell morphology of extrusion foamed poly(lactic acid) using endothermic chemical foaming agent

Poly(lactic acid) (PLA) was foamed with an endothermic chemical foaming agent (CFA) through an extrusion process. The effects of polymer melt flow index, CFA content, and processing speed on the cellular structures, void fraction, and cell-population density of foamed PLA were investigated. The apparent melt viscosity of PLA was measured to understand the effect of melt index on the cell morphology of foamed PLA samples. The void fraction was strongly dependent on the PLA melt index. It increased with increasing melt index, reaching a maximum value, after which it decreased. Melt index showed no significant effect on the cell-population density of foamed samples within the narrow range studied. A gas containment limit was observed in PLA foamed with CFA. Both the void fraction and cell-population density increased with an initial increase in CFA content, reached a maximum value, and then decreased as CFA content continued to increase. The processing speed also affected the morphology of PLA foams. The void fraction reached a maximum value as the extruder’s screw speed increased to 40 rpm and a further increase in the processing speed tended to reduce the void fraction of foamed samples. By contrast, cell-population density increased one order of magnitude by increasing the screw speed from 20 to 120 rpm. The experimental results indicate that a homogeneous and finer cellular morphology could be successfully achieved in PLA foamed in an extrusion process with a proper combination of polymer melt flow index, CFA content, and processing speed.     

Effects of chronic ethanol treatment on glial fibrillary acidic protein expression in adult rat optic nerve: an immunocytochemical study

Glial fibrillary acidic protein (GFAP) is used as a marker of astrocyte response to various central nervous system injuries. In the present study, the effects of chronic ethanol administration on GFAP immunoreactivity were evaluated in astrocytes of the adult optic nerve head. The results demonstrated that ethanol exposure significantly and dramatically increases GFAP immunoreactivity and the number of immunoreactive astrocytes (p<0.001). In addition, GFAP immunoreactive cells in the optic nerve showed extensive hypertrophy (p<0.001).     

Finding differentially expressed genes for pattern generation

MOTIVATION: It is important to consider finding differentially expressed genes in a dataset of microarray experiments for pattern generation. RESULTS: We developed two methods which are mainly based on the q-values approach; the first is a direct extension of the q-values approach, while the second uses two approaches: q-values and maximum-likelihood. We present two algorithms for the second method, one for error minimization and the other for confidence bounding. Also, we show how the method called Patterns from Gene Expression (PaGE) (Grant et al., 2000) can benefit from q-values. Finally, we conducted some experiments to demonstrate the effectiveness of the proposed methods; experimental results on a selected dataset (BRCA1 vs BRCA2 tumor types) are provided. CONTACT: alhajj@cpsc.ucalgary.ca.     

Evaluation of structural changes induced by high hydrostatic pressure in Leuconostoc mesenteroides

Scanning electron microcopy (SEM), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC) were used to evaluate structural changes in Leuconostoc mesenteroides cells as a function of high-hydrostatic-pressure treatment. This bacterium usually grows in chains of cells, which were increasingly dechained at elevated pressures. High-pressure treatments at 250 and 500 MPa also caused changes in the external surface and internal structure of cells. Dechaining and blister formation on the surface of cells increased with pressure, as observed in SEM micrographs. TEM studies showed that cytoplasmic components of the cells were affected by high-pressure treatment. DSC studies of whole cells showed increasing denaturation of ribosomes with pressure, in keeping with dense compacted regions in the cytoplasm of pressure-treated cells observed in TEM micrographs. Apparent reduction of intact ribosomes observed in DSC thermograms was related to the reduction in number of viable cells. The results indicate that inactivation of L. mesenteroides cells is mainly due to ribosomal denaturation observed as a reduction of the corresponding peak in DSC thermograms and condensed interior regions of cytoplasm in TEM micrographs.