Study of microstructure of oriented PET fibres exposed to supercritical carbon dioxide

Samples of partially oriented yarn (POY) PET fibers were uniaxially drawn at temperatures below, near, and above the glass transition temperature at a constant draw ratio before exposure to supercritical carbon dioxide (scCO₂) in the presence of tension at a temperature of 80 °C and a pressure of 220 bar. The effects of drawing temperature and scCO₂ exposure on structural changes and on mesomorphic transitions, in particular, were investigated using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and birefringence and density measurements. A good correlation was obtained among the results obtained from various techniques. Results indicated that the development of a transient mesophase structure depended strongly on process temperature. By drawing PET fibers in the samples at temperatures below the glass transition (cold-drawing), a mesophase structure developed in which the highly extended chains played a key role in structural changes incurred. Meanwhile, exposure to scCO₂ led to the plasticization of the samples accompanied by their reduced glass transition and cold crystallization temperatures. This process also gave rise to the appearance of a second melting peak at about 135 °C that is related to the melting of imperfect and thin crystals, thereby inducing structural changes in the treated fibers. In the case of samples subjected to cold drawing and to scCO₂ exposure, the transformation of the mesophase structure into the crystalline phase was found to be strongly affected by scCO₂ exposure, while this same effect was negligible in the case of hot drawn samples.     

Soil application of entomopathogenic nematodes suppresses the root-knot nematode Meloidogyne javanica in cucumber

Journal of Plant Diseases and Protection - Cucumber (Cucumis sativus) cultivation in commercial greenhouses occupies an important section of vegetable production in Iran. Root-knot nematode...     

Probiotics as beneficial microbes in aquaculture: an update on their multiple modes of action: a review

Wide and discriminate use of antibiotics has resulted in serious biological and ecological concerns, especially the emergence of antibiotic resistance. Probiotics, known as beneficial microbes, are being proposed as an effective and eco-friendly alternative to antibiotics. They were first applied in aquaculture species more than three decades ago, but considerable attention had been given only in the early 2000s. Probiotics are defined as live or dead, or even a component of the microorganisms that act under different modes of action in conferring beneficial effects to the host or to its environment. Several probiotics have been characterized and applied in fish and a number of them are of host origin. Unlike some disease control alternatives being adapted and proposed in aquaculture where actions are unilateral, the immense potential of probiotics lies on their multiple mechanisms in conferring benefits to the host fish and the rearing environment. The staggering number of probiotics papers in aquaculture highlights the multitude of advantages from these microorganisms and conspicuously position them in the dynamic search for health-promoting alternatives for cultured fish. This paper provides an update on the use of probiotics in finfish aquaculture, particularly focusing on their modes of action. It explores the contemporary understanding of their spatial and nutritional competitiveness, inhibitory metabolites, environmental modification capability, immunomodulatory potential and stress-alleviating mechanism. This timely update affirms the importance of probiotics in fostering sustainable approaches in aquaculture and provides avenues in furthering its research and development.     

Hematology of great sturgeon (<Emphasis Type="Italic">Huso huso</Emphasis> Linnaeus, 1758) juvenile exposed to brackish water environment

The effect of environmental salinity on hematological parameters of great sturgeon Huso huso juveniles was studied. Five-month-old juveniles (mean body weight 28.3 ± 2.1 g) were subjected to 0, 3, 6, 9, and 12 ppt salinities. The hematological parameters were assessed after a period of 20 days rearing at these salinities. After transfer from fresh water to brackish water, red blood cells, hematocrit, haemoglobin and mean corpuscular haemoglobin decreased, but mean corpuscular volume increased. Mean corpuscular haemoglobin concentration, white blood cells, monocyte counts, and eosinophil counts showed no significant variations with increase in environmental salinity. An increase was found in lymphocyte counts according to the increase of salinity from 0 to 12 ppt, while the fresh water control group maintained basal levels. Decrease in neutrophil counts was observed in great sturgeon with increase in environmental salinity. These data show significant effect of salinity on the blood parameters of great sturgeon.     

Targeted Deletion of Los1 Homologue Affects the Production of a Recombinant Model Protein in Pichia pastoris

Background:The methylotrophic yeast Pichia pastoris is an appealing production host for a variety of recombinant proteins, including biologics. In this sense, various genetic- and non-genetic-based techniques have been implemented to improve the production efficiency of this expression platform. Los1 (loss of supression) encodes a non-essential nuclear tRNA exporter in Saccharomyces cerevisiae, which its deletion extends RLS. Herein, a los1-deficient strain of P. pastoris was generated and characterized. Methods:A gene disruption cassette was prepared and transformed into an anti-CD22-expressing strain of P. pastoris. A δ los1 mutant was isolated and confirmed. The drug sensitivity of the mutant was also assessed. The growth pattern and the level of anti-CD22 ScFv expression were compared between the parent and mutant strains.Results:The los1 homologue was found to be a non-essential gene in P. pastoris. Furthermore, the susceptibility of los1 deletion strain to protein synthesis inhibitors was altered. This strain showed an approximately 1.85-fold increase in the extracellular level of anti-CD22 scFv (p < 0.05). The maximum concentrations of total proteins secreted by δ los1 and parent strains were 125 mg/L and 68 mg/L, respectively.Conclusion:The presented data suggest that the targeted disruption of los1 homologue in P. pastoris can result in a higher expression level of our target protein. Findings of this study may improve the current strategies used in optimizing the productivity of recombinant P. pastoris strains. Key Words: Aging, Longevity, Pichia pastoris, Recombinant proteins     

Effects of dietary administration of Echinacea purpurea on growth indices and biochemical and hematological indices in rainbow trout (Oncorhynchus mykiss) fingerlings

This study was conducted to evaluate the effects of Echinacea purpurea (EP) on growth and some hematological and blood biochemical indices of rainbow trout fingerlings. A basal diet was supplemented with 0 (control), 0.25, 0.5, 1, and 2 g EP kg?1 to formulate five experimental diets. Each diet was randomly allocated to triplicate groups of fish with an initial average weight of approximately 8 g. After 8 weeks of feeding trial, fish fed diets with 0.25 and 0.5 g EP kg?1 showed highest final weight and SGR and fish fed with the control diet indicated the lowest final weight and SGR. There was a significant (P < 0.05) decrease in FCR between the control group and the groups fed with diets of 0.25 and 0.5 g EP kg?1. Biochemical parameters such as serum total protein content, albumin content, globulin content, and albumin/globulin ratio in the fish were evaluated. There were significant differences between hematological parameters including RBC, WBC, HB, lymphocyte, and neutrophil percentage in fish fed with dietary nucleotide compared with control treatment (P < 0.05). The results suggest that EP administration at 0.25 and 0.5 g EP kg?1 exerted positive effects on growth and biochemical and hematological indices in rainbow trout.     

Effect of dietary willow herb,Epilobium hirsutum extract on growth performance,body composition,haematological parameters and Aeromonas hydrophila challenge on common carp,Cyprinus carpio

The present study was conducted to evaluate the use of Epilobium hirsutum extract in diet of common carp, Cyprinus carpio (20 ± 2 g). Different levels of plant extract (0%, 0.5%, 1, 3% and 3%+2‰ multivitamin (2 g of multivitamin per kg diet) were spread on commercial diet. The feed was offered by 8 weeks. Results showed that fish fed experimental diets had no significant difference (P>0.05) in specific growth rates, condition factor, feed conversion ratios and survival compared with control. There were no significant difference (P>0.05) in moisture, crude protein, crude lipid and ash content of common carp fed diets containing various levels of plant extract. The mortality of fish challenged by Aeromonas hydrophila have been recorded for 30 days after challenging, results showed that mortality decreased significantly (P<0.05) in fish fed diet containing plant extract compared with the control. The lowest mortality observed in group fed diet containing 3% plant extract. Haematological parameters showed that white blood cells had significantly (P<0.05) increased in infected and uninfected groups compared with the control. Red blood cells, haemoglobin and haematocrit had no significant change (P>0.05) in infected and uninfected groups compared with the control.     

Prevalence of thin-walled <Emphasis Type="Italic">Sarcocystis cruzi</Emphasis> and thick-walled <Emphasis Type="Italic">Sarcocystis hirsuta</Emphasis> or <Emphasis Type="Italic">Sarcocystis hominis</Emphasis> from cattle in Iran

Bovine sarcocystosis is caused by Sarcocystis cruzi and is known to cause considerable morbidity and mortality in cattle. This species is distributed worldwide in cattle and is the most prevalent of the Sarcocystis species infecting cattle. There is high infection rate of sarcocyst in cattle in Iran, but to our knowledge, there is no study about identification of Sarcocystis species. This work aimed to survey prevalence of S. cruzi cyst in slaughtered cattle of Isfahan, Iran. In this study, esophageal and diaphragmatic muscles of 100 cattle were collected from Fesaran abattoir of Isfahan and examined for the presence of Sarcocystis spp. cysts macroscopically and microscopically. No macroscopic sarcocysts were found in any of the samples. In light microscopy, 89 out of 100 cattle (89%) had thin-walled cysts of S. cruzi, while 21 out of them (21%) had thick-walled sarcocysts. In addition to light microscopy, ultrastructural features of the thin-walled cyst confirmed the presence of S. cruzi.     

Developing a dynamic yield and growth model for maize under various water and nitrogen regimes

Better irrigation and nitrogen (N) scheduling and more efficient management of crop production require modeling of plant growth and crop yield. Models become more applicable if they are simple and require less and accessible inputs. The objective of this study was to use simple equations of soil water budget, evapotranspiration (ET), leaf area index (LAI), yield, and harvest index (HI)–transpiration function to develop a model for the prediction of growth and yield of maize under various water and N rates. The model was calibrated based on given data under sprinkler irrigation and verified based on independent data under furrow irrigation. The comparison between predicted and measured values of different crop parameters did not show any significant difference and the model was able to estimate LAI, ET, soil water content, HI, dry matter, and grain yield properly. Furthermore, an equation was presented to predict daily dry matter accumulation by a logistic curve for different water and N applications. It was concluded that the presented simple model was able to predict crop yield quite well and hence could be used for farm irrigation and N scheduling and management of both. Furthermore, the relationship between LAI and ET may be different in various environmental conditions that should be considered in using the model.     

Effect of quorum quenching bacteria on growth,virulence factors and biofilm formation of Yersinia ruckeri in vitro and an in vivo evaluation of their probiotic effect in rainbow trout

Five N‐acyl homoserine lactone‐degrading bacteria (quorum quenching (QQ) strains) were selected to evaluate their impacts on growth, virulence factors and biofilm formation in Yersinia ruckeri in vitro. No difference was observed among the growth pattern of Y. ruckeri in monoculture and coculture with the QQ strains. To investigate the regulation of virulence factors by quorum sensing in Y. ruckeri, cultures were supplemented with 3oxo‐C8‐HSL. The results indicated that swimming motility and biofilm formation are positively regulated by QS (p < 0.05), whereas caseinase, phospholipase and haemolysin productions are not influenced by 3oxo‐C8‐HSL (p > 0.05). The QQs were able to decrease swimming motility and biofilm formation in Y. ruckeri. QQ bacteria were supplemented to trout feed at 10⁸ CFU/g (for 40 days). Their probiotic effect was verified by Y. ruckeri challenge either by immersion or injection in trout. All strains could significantly increase fish survival with Bacillus thuringiensis and Citrobacter gillenii showing the highest and lowest relative percentage survival (RPS) values (respectively, 85% and 38%). Besides, there was no difference between the RPS values by either immersion or injection challenge expect for B. thuringiensis. The putative involvement of the QQ capacity in the protection against Yersinia is discussed.