The role of flatfishes in the organization and structure of the eastern Bering Sea ecosystem

We evaluated the role of flatfishes in the organization and structure of the eastern Bering Sea ecosystem using the Ecopath/Ecosim approach. As basic input data for the Ecopath/Ecosim model, we used estimates of biomass from bottom trawl surveys and age-structured population models, production/biomass (P/B) ratio, consumption/biomass (Q/B) ratio, diet composition (DC), and fisheries harvests for each component of species or species groups. We estimated the trophic level of each component, niche overlaps among flatfishes, and the impacts of competition and predation on flatfish species in the eastern Bering Sea ecosystem. Based on those estimates, we developed the tropho-dynamic structure of the ecosystem, and the model was used to simulate ecological effects of fishery exploitation patterns. No single flatfish species appeared to have a profound and uniquely important role in the organization and structure of the ecosystem. Instead, the most important component among the guild of flatfish species appeared to be yellowfin sole Pleuronectes asper, which had greater biomass than other flatfish and a relatively diverse diet among the small flatfish species. Pacific halibut Hippoglossus stenolepis, Greenland turbot Reinhardtius hippoglossoides, and arrowtooth flounder Atheresthes stomias were important keystone predators in the eastern Bering Sea ecosystem together with some groups of marine mammals and sea birds. Intra flatfish complex cannibalism was not observed, however, substantial diet overlaps were common in the flatfish guild system.     

Critical nutrient concentrations and antagonistic and synergistic relationships among the nutrients of NFT‐grown young tomato plants

Critical concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), and manganese (Mn) with respect to dry matter yield end antagonistic and synergistic relationships among these nutrients were studied in which tomato (Lycopersicon esculentum L.) was grown in recirculating nutrient solution (NFT). Increments of nutrient elements in the nutrient solution increased the proportional rate of the corresponding nutrient elements. Increasing levels of N negatively correlated with plant P and positively correlated with Ca, Fe, and Zn. Iron and Mn contents of the plants were increased and N, K, Ca, and Mg were decreased as a function of P applied. Increases in K in the nutrient solution caused increases in the concentrations of K, N, P, and Zn, and decreases in the concentration of Ca and Fe. Applied Ca increased the concentrations of Ca and N, and decreased the concentrations of P, Mg, Fe, Zn, and Mn. Potassium, Ca, and Fe contents of the plants were decreased and Zn increased, while N, P, and Mn were not affected by the increasing levels of external Mg. Iron suppressed the plant Mg, Zn, and Mn contents. Synergism between Zn and Fe was seen, while P, K, Ca, Mg, and Mn contents were not affected by Zn levels. Potassium, Ca, Mg, and Fe were not responsive to applied Mn, however, N and P contents of the plants were decreased at the highest levels of Mn.     

Influence of growing season and donor plant age on anther culture response of some pepper cultivars (Capsicum annuum L.)

The effects of growing season and donor plant age on anther culture in Capsicum were investigated. Pepper cultivars Kekova and Sera Demre 8 were grown under unheated greenhouse conditions in winter season and field conditions in summer season. Flower buds were collected and cultured in weekly intervals from November to May in winter and from April to December in summer. The results of this study indicated that anthers from these two pepper genotypes gave different embryogenic response to seasonal effects. Kekova cultivar gave the highest embryogenic yield in summer season while this was occurred in winter season for Sera Demre 8 cultivar. The results of the study revealed that the effect of donor plant age was also an important factor in anther culture of pepper. Since 4-month-old plants gave the highest embryo yield in both cultivars in each seasons, it is possible to say that anthers collected from old plants have sufficient embryogenic response when the optimum developmental stage is selected.     

Genetic analysis of selected almond genotypes and cultivars grown in Turkey using peroxidase-gene-based markers

Peroxidase plays important roles in many stress-related interactions and catalyzes important reactions in various physiological processes. Since peroxidase played critical roles in the evolution of almond(Prunus dulcis Miller(D.A Webb) syn P. amygdalus Batsch), peroxidase-gene-based analyses may increase the understanding of evolution of this species. Peroxidase gene polymorphism(POGP) markers were used to determine genetic diversity and relationships among 69 Turkish genotypes/cultivars and 27 foreign almond cultivars by using unweighted pair group method with arithmetic mean(UPGMA) analysis. This study is the first evaluation of the use of POGP markers for diversity analysis in almond.Totally, 83 fragments were obtained from eight peroxidase primer pairs, and polymorphism was identified as 94 %.Similarity level among the genotypes ranged between 0.63 and 0.93, and all materials were distinguished. In general,Turkish and foreign genotypes were mixed in clusters since they share a common genetic background and gene migration among the sites. Clusters were not based on geographic regions except for some minor groupings. This study indicated that peroxidase gene markers can be reliably used to determine genetic relationships in almonds.     

The effect of various nitrogen fertilizers on zinc (zn) availability in non calcic brown forest soils

In this article the effect of different nitrogen fertilizer application on the availability of zinc (Zn) content in non calcic brown forest soil was investigated. For this purpose increasing rates of NH₄Cl, (NH₄)₂S0₄; NH₄N0₃ and Ca(N0₃)₂.4H₂0 fertilizers were applied for having different physical and chemical properties in two soil samples. An incubation experiment was carried out over 4 months. The available Zn content of the soils was determined each month. According to the results the highest available Zn content of the soils was obtained from NH₄Cl applied to the soils followed by (NH₄)₂S0₄; NH₄N0₃ and Ca(N0₃)₂.4H₂0 application to soil. At the end of the experiment the average available Zn content of non calcic brown forest soils for NH₄Cl, (NH₄)₂S0₄; NH₄N0₃ and Ca(N0₃)₂.4H₂0 fertilizers are 0.93, 0.91, 0.88 and 0.77 mg kg^?1, respectively.     

Effect of Water Stress at Various Growth Stages on Some Quality Characteristics of Winter Wheat

A field experiment was carried out in Erzurum (Turkey) on winter wheat to analyse the effect of water stress at different growth stages – fully irrigated (FI), rainfed (R), early water stress (EWS), late water stress (LWS) and continuous water stress (CWS), on some quality characteristics – in the 1995–96 and 1996–97 cropping seasons. Water stress had a substantial effect on most of the quality characteristics. As averages of cropping seasons, CWS, EWS, R and LWS treatments decreased grain yields by 65.5, 40.6, 30.5 and 24.0 %, respectively, compared with the FI treatment. CWS increased grain protein content by 18.1 %, sedimentation volume by 16.5 %, wet gluten content by 21.9 % and decreased 1000‐kernel weight by 7.5 g compared with FI treatment. LWS caused an increase of 8.3 % in grain protein content, 8.7 % in sedimentation volume, 10.8 % in wet gluten content and a reduction of 3.8 g in 1000‐kernel weight compared with FI. EWS and R increased sedimentation volume and wet gluten content, but decreased 1000‐kernel weight compared with FI. The effect of LWS on grain quality was more significant than that of EWS. The results suggest that soil moisture conditions increase grain yield and kernel weight of winter wheat but decrease its quality.     

Determination of suitable chemical extraction methods for the available iron content of brown forest soils in Turkey

The aim of this research was to determine the available iron (Fe) content of brown forest soils of Edirne Province and the most suitable chemical extraction method. Eight chemical extraction methods (the 0.005 M DTPA + 0.01 M CaCl2 + 0.1 MTEA, 0.05 M HCl + 0.012 M H2SO4, 1 M NH4OAc (pH: 4.8), 0.01 M EDTA + 1 M NH4OAc, 1 M MgCl2, 0.01 M EDTA + 1 M (NH4)2CO3, 0.005 M DTPA + 1 M NH4HCO3, and 0.001 M EDDHA methods) and six biological indices (the dry matter yield, Fe concentration, Fe uptake, relative dry matter yield, relative Fe concentration, and relative Fe uptake) were compared. The biological indices were determined with barley (Hordeum vulgare L.) grown under greenhouse conditions. At the end of the experiment, the highest correlation coefficients (r) were determined to be between the 0.005 M DTPA + 0.01 M CaCl2 + 0.1 M TEA method and the biological indices and between the 0.005 M DTPA + 1 M NH4HCO3 method and the biological indices. The corresponding correlation coefficients (r) for the 0.005 M DTPA + 0.01 M CaCl2 + 0.1 M TEA method and the six biological indices were 0.621**, 0.823**, 0.810** 0.433**, 0.558**, and 0.640**, respectively. For the 0.005 M DTPA + 1 M NH4HCO3 method, these coefficients were equal to 0.618**, 0.520**, 0.679**, 0.521**, 0.492**, and 0.641**, respectively (** indicate the validity of the relationships at p < 0.01) These extraction methods, out of all the methods tested, were suggested for the determination of the available Fe content of the brown forest soils. Published in Russian in Pochvovedenie, 2006, No. 9, pp. 1068–1074. The text was submitted by the author in English.     

Molecular and pathological investigations of EHV-1 and EHV-4 infections in horses in Turkey

The aim of the present study was to investigate abortion storms that occurred in the Marmara region of Turkey in 2008-2009 using a real-time PCR. Two aborted foetuses were necropsied and histo-pathological findings reported herein. Ten lungs, 3 brains and one nasal swab from 10 aborted foetuses, 6 nasal swabs and 3 vaginal swabs from aborting mares were included in this study. EHV-1 was isolated from the lung, liver and brain of 1 aborted foetus. EHV-1 DNA was detected in the lungs, livers and spleens of 2 necropsied foetuses and in 3 lungs from 10 foetuses submitted for diagnosis. A brain from one of the aborted foetuses was also positive for EHV-1 DNA. EHV-4 DNA was detected only in a nasal swab of one of the tested foetuses. Neither EHV-1 nor EHV-4 DNA was detected in the swabs of aborting mares. Sequence analysis of the glycoprotein B of the strains was performed and a phylogenetic tree was generated. The results indicated that 4 of the 5 Turkish EHV-1 strains (TR02, TR03, TR04 and TR05) clustered together; the fifth strain (TR01) was slightly removed from the group and clustered with other EHV-1 from various origins. Single nucleotide polyporphism (SNP in ORF30) associated with neuropathogenesis was not detected in any of the strains. At necropsy, sub-milier focal necrosis in the liver and spleen was observed. Microscopically, focal coagulation necrosis and marked eosinophilic intranuclear and intracytoplasmic inclusion bodies in the hepatocytes localised around the necrotic areas in the liver. Severe coagulation necrosis in white pulp of the spleen was also observed.     

Genetic basis of penicillin resistance of S. aureus isolated in bovine mastitis

Background

The blaZ gene encoding penicillin resistance can be located either chromosomally or on plasmids. The aim of this study was to investigate the genetic relationships and to determine the location of the blaZ gene in S. aureus isolated in bovine mastitis in Finland and Sweden.

Methods

Seventy-eight β-lactamase positive S. aureus isolates from bovine mastitis (34 from Finland and 44 from Sweden) were included in the study. The localization of blaZ gene was determined by Southern blotting. The blaZ genes of the isolates were sequenced and the sequences were translated to beta-lactamase proteins and further grouped as different protein signatures. The isolates and, as control, 33 Swedish and 36 Finnish beta-lactamase negative isolates were typed with pulsed-field gel electrophoresis (PFGE).

Results

In 26 out of 34 Finnish isolates (76.5%) and in 25 out of 44 Swedish isolates (56.8%) the blaZ gene was localized on a plasmid. Six different protein signatures were found. One signature was found only in four Swedish isolates, but all other signatures were found both in Finnish and Swedish isolates. The PFGE results revealed a diversity of S. aureus clones. The protein signatures were not clearly associated with certain pulsotypes.

Conclusions

The plasmid location of the blaZ gene was not statistically significantly more common in Finland than in Sweden, and hence does not explain the higher proportion of penicillin-resistant isolates of S. aureus causing bovine mastitis in Finland compared to Sweden.