Population dynamics and biological characteristics of kilka species (Pisces: Clupeonidae) in the southeastern coast of the Caspian Sea

The aim of the present study was to investigate the age structure, length-weight relationship, sex ratio, sexual maturity stages, growth parameters, natural and fishing mortality coefficients of three species of kilka including common, anchovy and bigeye kilka. The fork length–weight relationship of common, anchovy and bigeye kilka were calculated as W=0.000153 FL2.37, W=0.000349 FL2.18 and W=0.00160 FL2.97, respectively. The parameters of the von Bertalanffy growth curve for length were L∞ = 143.5 mm, K = 0.30 yr-1 and t0 = -1.02 yr for common kilka L∞ = 151.9 mm, K = 0.28 yr-1 and t0 = -1.12 yr for anchovy kilka L∞ = 148.6 mm, K = 0.46 yr-1 and t0 = -0.18 yr for bigeye kilka. The instantaneous coefficient of natural mortality of common, anchovy and bigeye kilka were estimated as 0.671, 0.633 and 0.881 yr-1, respectively. The current exploitation rates of three species were estimated as 0.55, 0.41 and 0.26, respectively. The results suggest that common kilka stock is under over-fishing now

Tween 80 coated alumina: An alternative support for solid phase extraction of copper, nickel, cobalt and cadmium prior to flame atomic absorption spectrometric determination

AbstractThe potential of coated alumina as a sorbent for the simultaneous separation and preconcentration of copper, nickel, cobalt and cadmium ions has been investigated. Copper, nickel, cobalt and cadmium were adsorbed quantitatively on coated alumina in the pH of 6. The main factors such as pH, amount sorbent, sample and eluent flow rate, type and volume of elution solution and interfering ions on the sorption of metal ions have been investigated in detail. Under the optimum experimental conditions, the detection limits (3Sb) of this method for Cu(II), Ni(II), Co(II) and Cd(II) ions were 0.4, 1.0, 1.2 and 0.2ngmL−1 in the original solution, respectively. Seven replicate determinations of a mixture of 5.0μg of Cu(II), Ni(II), Co(II) and 1.0μg of Cd(II) ions in the original solution gave a mean absorbance of 0.093, 0.071, 0.066 and 0.049 with relative standard deviations 1.9%, 2.3%, 2.6% and 2.1%, respectively. The method has been applied for the determination of trace amounts of Cu(II), Ni(II), Co(II) and Cd(II) ions in tobacco, brewed tea and water samples with satisfactory results

Immune system challenge in a host-parasitoid-pathogen system: interaction between Cotesia plutellae (Hym.: Braconidae) and Bacillus thuringiensis influences parasitism and phenoloxidase cascade of Plutella xylostella (Lep.: Plutellidae)

We investigated the effects of interaction between Cotesia plutellae (Kurdjumov) and Bacillus thuringiensis Berliner on parasitism and an immune effector (phenoloxidase activity) of a Bt-susceptible and a Bt-resistant population of Plutella xylostella (Linnaeus) in laboratory. Parasitism success of C. plutellae varied depending on the use of B. thuringiensis or its toxin, and the timing of application. Percentage parasitism was significantly greater on Cry1Ac-treated hosts than B. thuringiensis var. kurstaki-treated hosts (the susceptible population), and greater when hosts were treated with B. thuringiensis var. kurstaki before parasitism compared to that after parasitism (the resistant population). Specific phenoloxidase activity was significantly reduced in Cry1Ac-treated or parasitized hosts, but combined effect of the toxin and the parasitoid caused a greater reduction in phenoloxidase activity. The lower phenoloxidase activity in unparasitized resistant population of P. xylostella compared with the susceptible one is likely to be due to fitness costs, manifesting a possible trade-off between pathogen resistance and parasitoid resistance. However, C. plutellae overwhelmingly suppressed phenoloxidase activity of both the susceptible and resistant populations of P. xylostella. We found that the interaction between B. thuringiensis and C. plutellae was synergistic, which is promising for integration of the pathogen and the parasitoid in management of P. xylostella populations

Mokrzeckia obscura (Hym.: Pteromalidae), a hyperparasitoid of diamondback moth and a new record from Iran

در بررسی‌های مربوط به شناسایی پارازیتوئیدهای مراحل نابالغ بید کلم، Plutella xylostella (L.) (Lep.: Plutellidae)، در مزارع کلم و کلم گل استان اصفهان، یک گونه پارازیتوئید ثانویه به نام Mokrzeckia obscura Graham از خانواده‌ی Pteromalidae جمع‌آوری و شناسایی شد که برای اولین‌بار از ایران گزارش می‌شود. این گونه از پرورش لاروهای بید کلم که توسط Cotesia plutellae (Kurdjumov) (Hym.: Braconidae) پارازیته شده بودند، به‌دست آمد

Studies on the stability of population equilibrium of the diamondback moth (Plutella xylostella (Lep.: Plutellidae)) using perturbation method

Nowadays, a basic understanding of population biology is necessary to establish ecological strategies of pest management. In the present study, the population behavior of the diamondback moth after a perturbation was examined. For this purpose, a long-term experiment with three treatments (control, a perturbation using density reduction and a perturbation using density increase) was performed. The experiment was started with 10 pairs of adult moths in ventilated cages under the standard constant environment. The experiment was continued for 10 generations. After five generations, the perturbation was applied and each treatment was replicated 10 times. Adults and larvae were fed with honey solution (20%) and Chinese cabbage, respectively. The population trend and stability were monitored by weekly census counts of live adults, and the data used as a measure of abundance for the population dynamics. The results showed that the populations of the diamondback moth persisted at equilibrial levels when there was no perturbation. On the contrary, when the populations were perturbed using density reduction, the population equilibrium was shifted to a lower level; in this situation perturbations using sustainable strategies, such as the release of natural enemies or the application of microbial insecticides, may set the equilibrium beneath economic injury threshold. While, a perturbation using density increase can cause instability of population equilibrium toward a decreasing trend that may drive the population to extinction. The causes and effects of the findings in relation with the moth life history, resource competition and its ecological consequences on the population behavior were discussed

Experimental and Finite Element Simulation of Wear in Nanostructured NiAl Coating

In this paper, the wear of nanostructured NiAl coating was studied both experimentally and numerically. First, the nanocrystalline NiAl intermetallic powder was synthesized by mechanical alloying (MA) of aluminum and Ni powders. The coatings were deposited onto the low carbon steel substrate using high velocity oxy-fuel (HVOF) technique. Nanoindentation test was conducted to find out the mechanical properties of the coating. The dry wear tests were then performed using a pin-on-block test rig under different operating conditions. Finally, finite element (FE) method was employed to model the wear characteristics of the prepared nanostructured material. A three-dimensional (3D) FE model was created and used to simulate the pin-on-block experiments. The results show that the volume losses predicted by the numerical analysis are in good agreement with the experimental data

Circular RNAs and gastrointestinal cancers: Epigenetic regulators with a prognostic and therapeutic role

Both environmental and genetic factors are involved in the initiation and development of gastrointestinal cancer. Covalent closed circular RNAs (circRNAs) are produced by a mechanism called �back-splicing� from mRNAs. They are highly stable and show cell and tissue specific expression patterns. Although some functions such as �microRNA sponge� and �RNA binding protein sponge� have been reported for a small number of circRNAs, the function of thousands of other circRNAs is still unknown. Dysregulation of circRNAs has been reported in many GI cancers and are involved in metastasis and invasion. CircRNAs have been reported to be useful as prognostic markers and targets for developing new treatments. We first describe the properties and biogenesis of circRNAs. We then summarize recent reports about circRNA functions, expression status, and their potential to be used as biomarkers in GI cancers including, gastric cancer, colorectal cancer, esophageal cancer, hepatocellular carcinoma, gallbladder cancer and pancreatic cancer. © 2019 Elsevier B.V

Autophagy in cancers including brain tumors: role of MicroRNAs

Autophagy has a crucial role in many cancers, including brain tumors. Several types of endogenous molecules (e.g. microRNAs, AKT, PTEN, p53, EGFR, and NF1) can modulate the process of autophagy. Recently miRNAs (small non-coding RNAs) have been found to play a vital role in the regulation of different cellular and molecular processes, such as autophagy. Deregulation of these molecules is associated with the development and progression of different pathological conditions, including brain tumors. It was found that miRNAs are epigenetic regulators, which influence the level of proteins coded by the targeted mRNAs with any modification of the genetic sequences. It has been revealed that various miRNAs (e.g., miR-7-1-3p, miR-340, miR-17, miR-30a, miR-224-3p, and miR-93), as epigenetic regulators, can modulate autophagy pathways within brain tumors. A deeper understanding of the underlying molecular targets of miRNAs, and their function in autophagy pathways could contribute to the development of new treatment methods for patients with brain tumors. In this review, we summarize the various miRNAs, which are involved in regulating autophagy in brain tumors. Moreover, we highlight the role of miRNAs in autophagy-related pathways in different cancers. Video abstract