Cylindrospermopsin directly disrupts spermatogenesis in isolated male zebrafish testis.

Cylindrospermopsin (CYN) is a cytotoxin, and its documented effects in mammals include damage to several organs. CYN also has hormone-disrupting properties, including estrogenic activity, progesterone production inhibition, and apoptosis induction. While CYN has been reported to exert reproductive toxicity in mice, little is known about its effect on fish reproductive function. Using ex vivo organ culture, we investigated the direct action of CYN on the male reproductive system. Isolated zebrafish testis was exposed to 250, 500, and 1000 µg/L CYN for 24 h and 7 d, followed by histo-morphological analysis. The results demonstrate that exposure to CYN led to a decrease in cell types from all three phases of spermatogenesis in zebrafish testis. There were also significant changes in fshr, lhr, and igf3 transcript levels, as well as testosterone secretion following exposure to CYN. In summary, this study provides novel information on the adverse effects of CYN on testicular spermatogenesis and male reproduction in zebrafish. These results provide a framework for a better understanding of CYN toxicity and the mechanism underlying the adverse action of CYN on male reproduction in fish.

Modelling and optimizing of calcium and non-phytate phosphorus requirements of male broiler chickens from 1 to 21 days of age using response surface methodology.

The skeleton is the main site of P and Ca deposition; therefore, accurate estimation of Ca and P requirements is necessary to maintaining health and optimum performance of broiler chickens. A response surface methodology (RSM) using a central composite design (CCD) was used for evaluating and optimizing of Ca and non-phytate P (NPP) requirements of broiler chickens for optimal performance, ileal nutrient digestibility and bone mineralization from 1 to 21 days of age. A total of 750 one-day-old male broiler chickens (Ross 308) were randomly distributed into 50 cages including 9 treatments, each replicated 5 times (except central treatment with 10 replicates) and 15 birds in each cage by CCD. The dietary Ca levels of 4.3, 5.6, 8.6, 11.7 and 13.0 g/kg and NPP of 2.5, 2.9, 4.0, 5.0 and 5.4 g/kg were used for nine treatments of CCD. The results indicated that the linear and quadratic effects of NPP, quadratic effects of Ca and Ca × NPP were significant for average weight gain (AWG, P < 0.05), average feed intake (AFI, P < 0.05), feed conversion ratio (FCR, P < 0.05) and Ca and P apparent ileal digestibility (AID, P < 0.05); however, the linear effect of Ca was significant only for FCR (P < 0.05). On the other hand, tibia and toe ash were affected by NPP (linear and quadratic, P < 0.01) and Ca (quadratic, P < 0.01). The second-order polynomial regression model was significant for AWG (R2 = 0.93, P < 0.001), AFI (R2 = 0.88, P < 0.001), FCR (R2 = 0.78, P < 0.001), AID of Ca (R2 = 0.78, P < 0.001) and P (R2 = 0.88, P < 0.001), tibia ash (R2 = 0.86, P < 0.001) and toe ash (R2 = 0.85, P < 0.001). The multi-objective optimization indicated that broiler chickens from 1 to 21 days of age need 7.03 and 4.47 g/kg of Ca and NPP, respectively, to achieve optimal AWG, FCR, tibia and toe ash. However, the dietary Ca and NPP levels can be reduced to 6.57 and 3.95 g/kg with a slight negative impact on performance and bone mineralization, respectively. In conclusion, the findings indicate that using multi-objective optimization model such as RSM provides more information regarding optimum Ca and NPP requirements of broiler chickens, considering the complex interaction between these two minerals. While the NPP levels are in line with current recommended requirements, Ca levels are considerably lower and suggest that current recommended Ca requirements may be in excess of the needs of the broiler.

Estimating the atmospheric correlation length with stochastic parallel gradient descent algorithm.

The atmospheric turbulence measurement has received much attention in various fields due to its effects on wave propagation. One of the interesting parameters for characterization of the atmospheric turbulence is the Fried parameter or the atmospheric correlation length. We numerically investigate the feasibility of estimating the Fried parameter using a simple and low-cost system based on the stochastic parallel gradient descent (SPGD) algorithm without the need for wavefront sensing. We simulate the atmospheric turbulence using Zernike polynomials and employ a wavefront sensor-less adaptive optics system based on the SPGD algorithm and report the estimated Fried parameter after compensating for atmospheric-turbulence-induced phase distortions. Several simulations for different atmospheric turbulence strengths are presented to validate the proposed method.

Adaptive phase aberration correction based on imperialist competitive algorithm.

We investigate numerically the feasibility of phase aberration correction in a wavefront sensorless adaptive optical system, based on the imperialist competitive algorithm (ICA). Considering a 61-element deformable mirror (DM) and the Strehl ratio as the cost function of ICA, this algorithm is employed to search the optimum surface profile of DM for correcting the phase aberrations in a solid-state laser system. The correction results show that ICA is a powerful correction algorithm for static or slowly changing phase aberrations in optical systems, such as solid-state lasers. The correction capability and the convergence speed of this algorithm are compared with those of the genetic algorithm (GA) and stochastic parallel gradient descent (SPGD) algorithm. The results indicate that these algorithms have almost the same correction capability. Also, ICA and GA are almost the same in convergence speed and SPGD is the fastest of these algorithms.

Demonstration of side coupling to cladding modes through zinc oxide nanorods grown on multimode optical fiber.

A novel concept is introduced that utilizes the scattering properties of zinc oxide nanorods to control light guidance and leakage inside optical fibers coated with nanorods. The effect of the hydrothermal growth conditions of the nanorods on light scattering and coupling to optical fiber are experimentally investigated. At optimum conditions, 5% of the incident light is side coupled to the cladding modes. This coupling scheme could be used in different applications such as distributed sensors and light combing. Implementation of the nanorods on fiber provides low cost and controllable nonlithography-based solutions for free space to fiber coupling. Higher coupling efficiencies can be achieved with further optimization.

Symmetric bursting behaviors in the generalized FitzHugh-Nagumo model.

In the current paper, we have investigated the generalized FitzHugh-Nagumo model. We have shown that symmetric bursting behaviors of different types could be observed in this model with an appropriate recovery term. A modified version of this system is used to construct bursting activities. Furthermore, we have shown some numerical examples of delayed Hopf bifurcation and canard phenomenon in the symmetric bursting of super-Hopf/homoclinic type near its super-Hopf and homoclinic bifurcations, respectively.

Inhibitory effect of methanol extract of Rosa damascena Mill. flowers on alpha-glucosidase activity and postprandial hyperglycemia in normal and diabetic rats.

The effect of a methanol extract of Rosa damascena Mill. flowers was studied, in comparison to the alpha-glucosidase inhibitor acarbose, in normal and diabetic rats. The inhibition mode of this extract was examined by measuring enzyme activity in different concentrations of substrate for Lineweaver-Burk plot analysis. The results show that Rosa damascena extract has an intensive inhibitory effect on alpha-glucosidase. Its inhibition was found to be noncompetitive. Oral administration of this plant extract (100 to 1000 mg/kg body wt.) significantly decreased blood glucose after maltose loading in normal and diabetic rats in a dose-dependent manner. These results suggest that Rosa damascena might exert an anti-diabetic effect by suppressing carbohydrate absorption from the intestine and can reduce the postprandial glucose level.

Detection of encephalitis viruses in mosquitoes (Diptera: Culicidae) and avian tissues.

ABSTRACT Diagnostic assays for the detection of St. Louis encephalitis (SLE) and western equine encephalomyelitis (WEE) viruses in mosquito pools and avian tissues were compared for sensitivity, accuracy and specificity. The in situ enzyme immunoassay (EIA), plaque assay on Vero cells, passage in Aedes albopictus Skuse C6/36 and C7/10 cells, antigen capture enzyme immunoassay (AC-EIA), and single and multiplex reverse transcription-polymerase chain reactions (RT-PCR) were evaluated using pools of 50 mosquitoes containing 1-2 experimentally infected individuals. RT-PCR was the most sensitive assay, with a detection limit of <0.1 plaque forming unit. AC-EIA was the fastest and most economical procedure, but was the least sensitive, detecting only 38% of positive pools. The in situ EIA included initial virus amplification on Vero cells, thereby improving assay sensitivity to detect 68% of positive pools. Passage in C6/36 and/or C7/10 cell culture revealed the presence of infectious virus in samples positive by RT-PCR, but initially negative by plaque assay on Vero cell culture, indicating that detection was related to assay sensitivity and not to the absence of intact infectious virus. Combining WEE and SLE RT-PCR assays into a multiplex assay reduced sensitivity, but stilldetected viral RNA at titers below plaque assay sensitivity. Plaque assay on Vero cells, mosquito cell passage, and several RT-PCR procedures were evaluated for their ability to detect WEE and SLE in white-crowned sparrow tissues during acute and chronic stages of infection. All assays detected virus during acute infection at times of high viremia; however, only RT-PCR assays were positive by day 7 when virus was not detected in sera. RT-PCR detected SLE RNA in spleen tissue from one bird 51 d after infection. Assay sensitivity also was compared using extracts of homogenized bird organs spiked with known titers of WEE and SLE. Trizol RNA extraction followed by Qiagen one-step RT-PCR was the most sensitive method, but occasionally resulted in the presence of secondary bands confounding interpretation and requiring confirmatory assays. A balanced surveillance program should combine systems that allow the detection of new agents and the sensitive monitoring of endemic agents to provide an early warning of pending health risks.

Detection of St. Louis encephalitis and western equine encephalomyelitis RNA in mosquitoes tested without maintenance of a cold chain.

Western equine encephalomyelitis and St. Louis encephalitis viral RNA can be detected 20 days after death of infected Culex tarsalis in the absence of a cold chain. Viral RNA was detected with the reverse transcription-polymerase chain reaction in mosquitoes infected either parenterally or perorally in the laboratory and then killed and held for up to 20 days at 27 degrees C. Cell culture assay and in situ enzyme immunoassay did not detect infectious virus in the same mosquitoes.

Genetic variation among isolates of western equine encephalomyelitis virus from California.

The mechanism for long-term maintenance of western equine encephalomyelitis (WEE) virus in California was investigated by studying genetic variation in the E2 portion of the genome of 55 strains of WEE virus isolated since 1938 from different locations in California. Four major lineages were evident: virus strains isolated from the Central Valley since 1993 and Los Angeles in 1991 formed lineage A; southern California strains isolated since 1978 and isolates from the Central Valley from 1978 to 1987 formed lineage B; northern California isolates from 1968 to 1971 formed lineage C; and early isolates from 1938 to 1961 formed a fourth lineage, D. The separation of strains from north and south of the Tehachapi and San Bernardino Mountains (i.e., the Central Valley and southern California, respectively) since 1991 indicates that there has been little recent movement of virus between the two regions and recent strains from these two locations appear to be evolving independently. However, within the Central Valley and within southern California, virus appears to circulate freely, perhaps by movement of birds or mosquito vectors. Although the current virus lineage in the Central Valley may have been introduced from an unknown source in 1991, introduction and establishment of new viral genotypes from outside California do not seem to occur regularly. It appears most likely that virus is maintained in separate geographic areas of California through local persistence in enzootic foci.

Regulatory mast cells. I Suppressive action of their products on an in vitro primary immune reaction.

Products of mast cell degranulation, as well as histamine and serotonin, were added to a Mishell and Dutton preparation for in vitro primary immunisation (induction of IgM antibody formation) to sheep or horse red blood cells. Degranulation products were either obatined beforehand by reacting passively sensitised mast cells with the corresponding antigen (unrelated to or identical with the in vitro immunising antigen) or liberated into the culture medium where mast cells actively sensitised to the in vitro immunising antigen had been added. A 46 to 72 % reduction of direct (IgM) plaque forming cells was observed in all cases. This reduction was prevented by anti-histamine. The responsible mediators were active in the 0 to 24 hour period after antigen introduction. The anaphylactic degranulating antibodies triggering this inhibitory activity were found to be thermolabile in one experiment. An in vivo-induced mast cell degranulation led to a reduced formation of plaque forming cells. The enhancing and immunoregulatory activity of anaphylactic mouse antibodies is therefore tentatively and at least partially attributed to their capacity to degranulate mast cells after contact with the antigen.